src/main/java/de/thm/arsnova/model/migration/FromV2Migrator.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import de.thm.arsnova.model.ChoiceAnswer;
+import de.thm.arsnova.model.ChoiceQuestionContent;
+import de.thm.arsnova.model.GridImageContent;
+import de.thm.arsnova.model.TextAnswer;
+import de.thm.arsnova.model.UserProfile;
+import de.thm.arsnova.model.migration.v2.Answer;
+import de.thm.arsnova.model.migration.v2.Comment;
+import de.thm.arsnova.model.migration.v2.Content;
+import de.thm.arsnova.model.migration.v2.DbUser;
+import de.thm.arsnova.model.migration.v2.Entity;
+import de.thm.arsnova.model.migration.v2.LoggedIn;
+import de.thm.arsnova.model.migration.v2.Motd;
+import de.thm.arsnova.model.migration.v2.MotdList;
+import de.thm.arsnova.model.migration.v2.Room;
+import de.thm.arsnova.model.migration.v2.RoomFeature;
+
+/**
+ * Converts legacy entities from version 2 to current model version.
+ *
+ * @author Daniel Gerhardt
+ */
+public class FromV2Migrator {
+	static final String V2 = "v2";
+	static final String V2_TYPE_ABCD = "abcd";
+	static final String V2_TYPE_SC = "sc";
+	static final String V2_TYPE_MC = "mc";
+	static final String V2_TYPE_VOTE = "vote";
+	static final String V2_TYPE_SCHOOL = "school";
+	static final String V2_TYPE_YESNO = "yesno";
+	static final String V2_TYPE_FREETEXT = "freetext";
+	static final String V2_TYPE_SLIDE = "slide";
+	static final String V2_TYPE_FLASHCARD = "flashcard";
+	static final String V2_TYPE_GRID = "grid";
+	static final String V2_GRID_DEFAULT_TYPE = "image";
+	static final String V2_GRID_TYPE = "gridType";
+	static final String V2_GRID_IMAGE_ABSOLUTE_X = "gridImageAbsoluteX";
+	static final String V2_GRID_IMAGE_ABSOLUTE_Y = "gridImageAbsoluteY";
+	static final String V2_GRID_MODERATION_DOT_LIMIT = "gridModerationDotLimit";
+	static final int V2_GRID_CONTAINER_SIZE = 400;
+	static final int V2_GRID_FIELD_COUNT = 16;
+	static final double V2_GRID_SCALE_FACTOR = 1.05;
+	private static final Map<String, de.thm.arsnova.model.Content.Format> formatMapping;
+
+	private boolean ignoreRevision = false;
+
+	static {
+		formatMapping = new HashMap<>();
+		formatMapping.put(V2_TYPE_ABCD, de.thm.arsnova.model.Content.Format.CHOICE);
+		formatMapping.put(V2_TYPE_SC, de.thm.arsnova.model.Content.Format.CHOICE);
+		formatMapping.put(V2_TYPE_MC, de.thm.arsnova.model.Content.Format.CHOICE);
+		formatMapping.put(V2_TYPE_VOTE, de.thm.arsnova.model.Content.Format.SCALE);
+		formatMapping.put(V2_TYPE_SCHOOL, de.thm.arsnova.model.Content.Format.SCALE);
+		formatMapping.put(V2_TYPE_YESNO, de.thm.arsnova.model.Content.Format.BINARY);
+		formatMapping.put(V2_TYPE_FREETEXT, de.thm.arsnova.model.Content.Format.TEXT);
+		formatMapping.put(V2_TYPE_SLIDE, de.thm.arsnova.model.Content.Format.TEXT);
+		formatMapping.put(V2_TYPE_FLASHCARD, de.thm.arsnova.model.Content.Format.TEXT);
+		formatMapping.put(V2_TYPE_GRID, de.thm.arsnova.model.Content.Format.GRID);
+	}
+
+	private void copyCommonProperties(final Entity from, final de.thm.arsnova.model.Entity to) {
+		to.setId(from.getId());
+		if (!ignoreRevision) {
+			to.setRevision(from.getRevision());
+		}
+	}
+
+	public UserProfile migrate(final DbUser dbUser, final LoggedIn loggedIn, final MotdList motdList) {
+		if (dbUser != null && loggedIn != null && !loggedIn.getUser().equals(dbUser.getUsername())) {
+			throw new IllegalArgumentException("Username of loggedIn object does not match.");
+		}
+		if (dbUser != null && motdList != null && !motdList.getUsername().equals(dbUser.getUsername())) {
+			throw new IllegalArgumentException("Username of motdList object does not match.");
+		}
+		if (loggedIn != null && motdList != null && !loggedIn.getUser().equals(motdList.getUsername())) {
+			throw new IllegalArgumentException("Usernames of loggedIn and motdList objects do not match.");
+		}
+		final UserProfile profile = new UserProfile();
+		if (dbUser != null) {
+			copyCommonProperties(dbUser, profile);
+			profile.setLoginId(dbUser.getUsername());
+			profile.setAuthProvider(UserProfile.AuthProvider.ARSNOVA);
+			profile.setCreationTimestamp(new Date(dbUser.getCreation()));
+			profile.setUpdateTimestamp(new Date());
+			final UserProfile.Account account = new UserProfile.Account();
+			profile.setAccount(account);
+			account.setPassword(dbUser.getPassword());
+			account.setActivationKey(dbUser.getActivationKey());
+			account.setPasswordResetKey(dbUser.getPasswordResetKey());
+			account.setPasswordResetTime(new Date(dbUser.getPasswordResetTime()));
+		}
+		if (loggedIn != null) {
+			if (dbUser == null) {
+				copyCommonProperties(loggedIn, profile);
+				updateProfileFromLoginId(profile, loggedIn.getUser());
+				profile.setCreationTimestamp(new Date());
+			}
+			profile.setLastLoginTimestamp(new Date(loggedIn.getTimestamp()));
+			final Set<UserProfile.RoomHistoryEntry> sessionHistory = loggedIn.getVisitedSessions().stream()
+					.map(entry -> new UserProfile.RoomHistoryEntry(entry.getId(), new Date(0)))
+					.collect(Collectors.toSet());
+			profile.setRoomHistory(sessionHistory);
+		}
+		if (motdList != null && motdList.getMotdkeys() != null) {
+			profile.setAcknowledgedMotds(migrate(motdList));
+		}
+
+		return profile;
+	}
+
+	public Set<String> migrate(final MotdList motdList) {
+		return Arrays.stream(motdList.getMotdkeys().split(",")).collect(Collectors.toSet());
+	}
+
+	public de.thm.arsnova.model.Room migrate(final Room from, final Optional<UserProfile> owner) {
+		if (!owner.isPresent() && from.getCreator() != null
+				|| owner.isPresent() && !owner.get().getLoginId().equals(from.getCreator())) {
+			throw new IllegalArgumentException("Username of owner object does not match session creator.");
+		}
+		final de.thm.arsnova.model.Room to = new de.thm.arsnova.model.Room();
+		copyCommonProperties(from, to);
+		to.setCreationTimestamp(new Date(from.getCreationTime()));
+		to.setUpdateTimestamp(new Date());
+		to.setShortId(from.getKeyword());
+		if (owner.isPresent()) {
+			to.setOwnerId(owner.get().getId());
+		}
+		to.setName(from.getName());
+		to.setAbbreviation(from.getShortName());
+		to.setDescription(from.getPpDescription());
+		to.setClosed(!from.isActive());
+		if (from.hasAuthorDetails()) {
+			final de.thm.arsnova.model.Room.Author author = new de.thm.arsnova.model.Room.Author();
+			to.setAuthor(author);
+			author.setName(from.getPpAuthorName());
+			author.setMail(from.getPpAuthorMail());
+			author.setOrganizationName(from.getPpUniversity());
+			author.setOrganizationUnit(from.getPpFaculty());
+			author.setOrganizationLogo(from.getPpLogo());
+		}
+		if ("public_pool".equals(from.getSessionType())) {
+			final de.thm.arsnova.model.Room.PoolProperties poolProperties = new de.thm.arsnova.model.Room.PoolProperties();
+			to.setPoolProperties(poolProperties);
+			poolProperties.setLevel(from.getPpLevel());
+			poolProperties.setCategory(from.getPpSubject());
+			poolProperties.setLicense(from.getPpLicense());
+		}
+		to.setSettings(migrate(from.getFeatures()));
+
+		return to;
+	}
+
+	public de.thm.arsnova.model.Room migrate(final Room from) {
+		return migrate(from, Optional.empty());
+	}
+
+	public de.thm.arsnova.model.Room.Settings migrate(final RoomFeature feature) {
+		final de.thm.arsnova.model.Room.Settings settings = new de.thm.arsnova.model.Room.Settings();
+		if (feature != null) {
+			settings.setCommentsEnabled(feature.isInterposed() || feature.isInterposedFeedback()
+					|| feature.isTwitterWall() || feature.isTotal());
+			settings.setQuestionsEnabled(feature.isLecture() || feature.isJitt() || feature.isClicker() || feature.isTotal());
+			settings.setSlidesEnabled(feature.isSlides() || feature.isTotal());
+			settings.setFlashcardsEnabled(feature.isFlashcardFeature() || feature.isFlashcard() || feature.isTotal());
+			settings.setQuickSurveyEnabled(feature.isLiveClicker());
+			settings.setQuickFeedbackEnabled(feature.isFeedback() || feature.isLiveFeedback() || feature.isTotal());
+			settings.setMultipleRoundsEnabled(feature.isPi() || feature.isClicker() || feature.isTotal());
+			settings.setTimerEnabled(feature.isPi() || feature.isClicker() || feature.isTotal());
+			settings.setScoreEnabled(feature.isLearningProgress() || feature.isTotal());
+		}
+
+		return settings;
+	}
+
+	public de.thm.arsnova.model.Content migrate(final Content from) {
+		final de.thm.arsnova.model.Content to;
+		final Map<String, Map<String, Object>> extensions;
+		final Map<String, Object> v2;
+		switch (from.getQuestionType()) {
+			case V2_TYPE_ABCD:
+			case V2_TYPE_SC:
+			case V2_TYPE_MC:
+			case V2_TYPE_VOTE:
+			case V2_TYPE_SCHOOL:
+			case V2_TYPE_YESNO:
+				final ChoiceQuestionContent choiceQuestionContent = new ChoiceQuestionContent();
+				to = choiceQuestionContent;
+				to.setFormat(formatMapping.get(from.getQuestionType()));
+				choiceQuestionContent.setMultiple(V2_TYPE_MC.equals(from.getQuestionType()));
+				for (int i = 0; i < from.getPossibleAnswers().size(); i++) {
+					final de.thm.arsnova.model.migration.v2.AnswerOption fromOption = from.getPossibleAnswers().get(i);
+					final ChoiceQuestionContent.AnswerOption toOption = new ChoiceQuestionContent.AnswerOption();
+					toOption.setLabel(fromOption.getText());
+					toOption.setPoints(fromOption.getValue());
+					choiceQuestionContent.getOptions().add(toOption);
+					if (fromOption.isCorrect()) {
+						choiceQuestionContent.getCorrectOptionIndexes().add(i);
+					}
+				}
+
+				break;
+			case V2_TYPE_FREETEXT:
+				to = new de.thm.arsnova.model.Content();
+				to.setFormat(de.thm.arsnova.model.Content.Format.TEXT);
+
+				break;
+			case V2_TYPE_SLIDE:
+				to = new de.thm.arsnova.model.Content();
+				to.setFormat(de.thm.arsnova.model.Content.Format.TEXT);
+				extensions = new HashMap<>();
+				to.setExtensions(extensions);
+				v2 = new HashMap<>();
+				extensions.put("v2", v2);
+				v2.put("format", V2_TYPE_SLIDE);
+
+				break;
+			case V2_TYPE_FLASHCARD:
+				to = new de.thm.arsnova.model.Content();
+				to.setFormat(de.thm.arsnova.model.Content.Format.TEXT);
+				extensions = new HashMap<>();
+				to.setExtensions(extensions);
+				v2 = new HashMap<>();
+				extensions.put("v2", v2);
+				v2.put("format", V2_TYPE_FLASHCARD);
+				if (!from.getPossibleAnswers().isEmpty()) {
+					to.setAdditionalText(from.getPossibleAnswers().get(0).getText());
+					to.setAdditionalTextTitle("Back");
+				}
+
+				break;
+			case V2_TYPE_GRID:
+				final GridImageContent gridImageContent = new GridImageContent();
+				to = gridImageContent;
+				to.setFormat(de.thm.arsnova.model.Content.Format.GRID);
+				final GridImageContent.Grid grid = gridImageContent.getGrid();
+				grid.setColumns(from.getGridSizeX());
+				grid.setRows(from.getGridSizeY());
+				grid.setNormalizedX(1.0 * from.getGridOffsetX() / V2_GRID_CONTAINER_SIZE);
+				grid.setNormalizedY(1.0 * from.getGridOffsetY() / V2_GRID_CONTAINER_SIZE);
+				/* v3 normalized field size = v2 scale factor ^ v2 zoom level / v2 grid size */
+				grid.setNormalizedFieldSize(Math.pow(Double.valueOf(from.getGridScaleFactor()), from.getGridZoomLvl())
+						/ from.getGridSize());
+				grid.setVisible(!from.getGridIsHidden());
+				final GridImageContent.Image image = gridImageContent.getImage();
+				image.setUrl(from.getImage());
+				image.setRotation(from.getImgRotation() * 90 % 360);
+				image.setScaleFactor(Math.pow(Double.valueOf(from.getScaleFactor()), from.getZoomLvl()));
+				gridImageContent.setCorrectOptionIndexes(from.getPossibleAnswers().stream()
+						.filter(o -> o.isCorrect())
+						.map(o -> {
+							try {
+								final String[] coords = (o.getText() != null ? o.getText() : "").split(";");
+								return coords.length == 2
+										? Integer.valueOf(coords[0]) + Integer.valueOf(coords[1]) * from.getGridSizeX()
+										: -1;
+							} catch (final NumberFormatException e) {
+								return -1;
+							}
+						})
+						.filter(i -> i >= 0 && i < grid.getColumns() * grid.getRows())
+						.collect(Collectors.toList()));
+				extensions = new HashMap<>();
+				to.setExtensions(extensions);
+				v2 = new HashMap<>();
+				extensions.put(V2, v2);
+				v2.put(V2_GRID_TYPE, from.getGridType());
+				/* It is not possible to migrate legacy image offsets to normalized values. */
+				if (from.getOffsetX() != 0) {
+					v2.put(V2_GRID_IMAGE_ABSOLUTE_X, from.getOffsetX());
+				}
+				if (from.getOffsetY() != 0) {
+					v2.put(V2_GRID_IMAGE_ABSOLUTE_Y, from.getOffsetY());
+				}
+				if (from.getNumberOfDots() != 0) {
+					v2.put(V2_GRID_MODERATION_DOT_LIMIT, from.getNumberOfDots());
+				}
+
+				break;
+			default:
+				throw new IllegalArgumentException("Unsupported content format.");
+		}
+		copyCommonProperties(from, to);
+		to.setRoomId(from.getSessionId());
+		to.getGroups().add(from.getQuestionVariant());
+		to.setSubject(from.getSubject());
+		to.setBody(from.getText());
+		to.setAbstentionsAllowed(from.isAbstention());
+		to.setAbstentionsAllowed(from.isAbstention());
+		if (from.getSolution() != null && !from.getSolution().isEmpty()) {
+			to.setAdditionalText(from.getSolution());
+			to.setAdditionalTextTitle("Solution");
+		} else if (from.getHint() != null && !from.getHint().isEmpty()) {
+			to.setAdditionalText(from.getHint());
+			to.setAdditionalTextTitle("Hint");
+		}
+		final de.thm.arsnova.model.Content.State state = to.getState();
+		state.setRound(from.getPiRound());
+		state.setVisible(from.isActive());
+		state.setResponsesVisible(from.isShowStatistic());
+		state.setAdditionalTextVisible(from.isShowAnswer());
+		state.setResponsesEnabled(!from.isVotingDisabled());
+
+		return to;
+	}
+
+	public de.thm.arsnova.model.Answer migrate(final Answer from, final de.thm.arsnova.model.Content content) {
+		final de.thm.arsnova.model.Answer answer;
+		if (content instanceof ChoiceQuestionContent || content instanceof GridImageContent) {
+			answer = migrateChoice(from, content);
+		} else {
+			answer = migrate(from);
+		}
+		answer.setFormat(content.getFormat());
+
+		return answer;
+	}
+
+	public TextAnswer migrate(final Answer from) {
+		final TextAnswer to = new TextAnswer();
+		copyCommonProperties(from, to);
+		to.setContentId(from.getQuestionId());
+		to.setRoomId(from.getSessionId());
+		to.setRound(from.getPiRound());
+		to.setSubject(from.getAnswerSubject());
+		to.setBody(from.getAnswerText());
+
+		return to;
+	}
+
+	public de.thm.arsnova.model.Comment migrate(final Comment from, @Nullable final UserProfile creator) {
+		if (creator == null && from.getCreator() != null
+				|| creator != null && !creator.getLoginId().equals(from.getCreator())) {
+			throw new IllegalArgumentException("Username of creator object does not match comment creator.");
+		}
+		final de.thm.arsnova.model.Comment to = new de.thm.arsnova.model.Comment();
+		copyCommonProperties(from, to);
+		to.setRoomId(from.getSessionId());
+		if (creator != null) {
+			to.setCreatorId(creator.getId());
+		}
+		to.setSubject(from.getSubject());
+		to.setBody(from.getText());
+		to.setTimestamp(new Date(from.getTimestamp()));
+		to.setRead(from.isRead());
+
+		return to;
+	}
+
+
+	public de.thm.arsnova.model.Comment migrate(final Comment from) {
+		return migrate(from, null);
+	}
+
+	public de.thm.arsnova.model.Motd migrate(final Motd from) {
+		final de.thm.arsnova.model.Motd to = new de.thm.arsnova.model.Motd();
+		copyCommonProperties(from, to);
+		to.setCreationTimestamp(from.getStartdate());
+		to.setUpdateTimestamp(new Date());
+		to.setStartDate(from.getStartdate());
+		to.setEndDate(from.getEnddate());
+		switch (from.getAudience()) {
+			case "all":
+				to.setAudience(de.thm.arsnova.model.Motd.Audience.ALL);
+				break;
+			case "tutors":
+				to.setAudience(de.thm.arsnova.model.Motd.Audience.AUTHORS);
+				break;
+			case "students":
+				to.setAudience(de.thm.arsnova.model.Motd.Audience.PARTICIPANTS);
+				break;
+			case "session":
+				to.setAudience(de.thm.arsnova.model.Motd.Audience.ROOM);
+				break;
+			default:
+				/* TODO: Add log message. */
+				break;
+		}
+		to.setTitle(from.getTitle());
+		to.setBody(from.getText());
+		to.setRoomId(from.getSessionId());
+
+		return to;
+	}
+
+	private ChoiceAnswer migrateChoice(final Answer from, final de.thm.arsnova.model.Content content) {
+		final ChoiceAnswer to = new ChoiceAnswer();
+		copyCommonProperties(from, to);
+		to.setContentId(from.getQuestionId());
+		to.setRoomId(from.getSessionId());
+		to.setRound(from.getPiRound());
+
+		if (from.isAbstention()) {
+			return to;
+		}
+
+		if (content instanceof ChoiceQuestionContent) {
+			final List<Integer> selectedChoiceIndexes = new ArrayList<>();
+			to.setSelectedChoiceIndexes(selectedChoiceIndexes);
+			final ChoiceQuestionContent choiceQuestionContent = (ChoiceQuestionContent) content;
+			if (choiceQuestionContent.isMultiple()) {
+				final List<Boolean> flags = Arrays.stream(from.getAnswerText().split(","))
+						.map("1"::equals).collect(Collectors.toList());
+				if (flags.size() != choiceQuestionContent.getOptions().size()) {
+					throw new IndexOutOfBoundsException(
+							"Number of answer's choice flags does not match number of content's answer options");
+				}
+				int i = 0;
+				for (final boolean flag : flags) {
+					if (flag) {
+						selectedChoiceIndexes.add(i);
+					}
+					i++;
+				}
+			} else {
+				int i = 0;
+				for (final ChoiceQuestionContent.AnswerOption option : choiceQuestionContent.getOptions()) {
+					if (option.getLabel().equals(from.getAnswerText())) {
+						selectedChoiceIndexes.add(i);
+						break;
+					}
+					i++;
+				}
+			}
+		} else if (content instanceof GridImageContent) {
+			final GridImageContent gridImageContent = (GridImageContent) content;
+			to.setSelectedChoiceIndexes(migrateChoice(from.getAnswerText(), gridImageContent.getGrid()));
+		} else {
+			throw new IllegalArgumentException(
+					"Content expected to be an instance of ChoiceQuestionContent or GridImageContent");
+		}
+
+		return to;
+	}
+
+	private List<Integer> migrateChoice(final String choice, final GridImageContent.Grid grid) {
+		return Arrays.stream(choice.split(","))
+			.map(c -> {
+				try {
+					final String[] coords = c.split(";");
+					return coords.length == 2
+							? Integer.valueOf(coords[0])
+							+ Integer.valueOf(coords[1]) * grid.getColumns()
+							: -1;
+				} catch (final NumberFormatException e) {
+					return -1;
+				}
+			})
+			.filter(i -> i >= 0
+				&& i < grid.getColumns() * grid.getRows())
+			.collect(Collectors.toList());
+	}
+
+	private void updateProfileFromLoginId(final UserProfile profile, final String loginId) {
+		if (loginId.length() == 15 && loginId.startsWith("Guest")) {
+			profile.setAuthProvider(UserProfile.AuthProvider.ARSNOVA_GUEST);
+			profile.setLoginId(loginId);
+		} else if (loginId.startsWith("$")) {
+			profile.setAuthProvider(UserProfile.AuthProvider.ANONYMIZED);
+			/* Remove redundant prefix and shorten ID to 10 chars */
+			profile.setLoginId(loginId.substring(loginId.lastIndexOf("$") + 1).substring(0, 10));
+		} else if (loginId.startsWith("oidc:")) {
+			profile.setAuthProvider(UserProfile.AuthProvider.OIDC);
+			profile.setLoginId(loginId.substring(5));
+		} else if (loginId.startsWith("saml:")) {
+			profile.setAuthProvider(UserProfile.AuthProvider.SAML);
+			profile.setLoginId(loginId.substring(5));
+		} else if (loginId.startsWith("https://www.facebook.com/") || loginId.startsWith("http://www.facebook.com/")) {
+			profile.setAuthProvider(UserProfile.AuthProvider.FACEBOOK);
+			/* Extract ID from URL */
+			profile.setLoginId(loginId.substring(loginId.indexOf("/", 23) + 1, loginId.length() - 1));
+		} else if (loginId.contains("@")) {
+			profile.setAuthProvider(UserProfile.AuthProvider.GOOGLE);
+			profile.setLoginId(loginId);
+		} else {
+			profile.setAuthProvider(UserProfile.AuthProvider.UNKNOWN);
+			profile.setLoginId(loginId);
+		}
+	}
+
+	public void setIgnoreRevision(final boolean ignoreRevision) {
+		this.ignoreRevision = ignoreRevision;
+	}
+}

src/main/java/de/thm/arsnova/model/migration/ToV2Migrator.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration;
+
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_CONTAINER_SIZE;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_DEFAULT_TYPE;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_FIELD_COUNT;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_IMAGE_ABSOLUTE_X;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_IMAGE_ABSOLUTE_Y;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_MODERATION_DOT_LIMIT;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_SCALE_FACTOR;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_GRID_TYPE;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_ABCD;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_FLASHCARD;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_FREETEXT;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_GRID;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_MC;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_SCHOOL;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_SLIDE;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_VOTE;
+import static de.thm.arsnova.model.migration.FromV2Migrator.V2_TYPE_YESNO;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import de.thm.arsnova.model.AnswerStatistics;
+import de.thm.arsnova.model.ChoiceQuestionContent;
+import de.thm.arsnova.model.GridImageContent;
+import de.thm.arsnova.model.RoomStatistics;
+import de.thm.arsnova.model.UserProfile;
+import de.thm.arsnova.model.migration.v2.Answer;
+import de.thm.arsnova.model.migration.v2.AnswerOption;
+import de.thm.arsnova.model.migration.v2.Comment;
+import de.thm.arsnova.model.migration.v2.Content;
+import de.thm.arsnova.model.migration.v2.Entity;
+import de.thm.arsnova.model.migration.v2.LoggedIn;
+import de.thm.arsnova.model.migration.v2.Motd;
+import de.thm.arsnova.model.migration.v2.MotdList;
+import de.thm.arsnova.model.migration.v2.Room;
+import de.thm.arsnova.model.migration.v2.RoomFeature;
+import de.thm.arsnova.model.migration.v2.RoomInfo;
+import de.thm.arsnova.model.migration.v2.VisitedRoom;
+
+/**
+ * Converts entities from current model version to legacy version 2.
+ *
+ * @author Daniel Gerhardt
+ */
+public class ToV2Migrator {
+
+	private void copyCommonProperties(final de.thm.arsnova.model.Entity from, final Entity to) {
+		to.setId(from.getId());
+		to.setRevision(from.getRevision());
+	}
+
+	public Room migrate(final de.thm.arsnova.model.Room from, final Optional<UserProfile> owner) {
+		final Room to = new Room();
+		copyCommonProperties(from, to);
+		to.setKeyword(from.getShortId());
+		if (owner.isPresent()) {
+			to.setCreator(owner.get().getLoginId());
+		}
+		to.setName(from.getName());
+		to.setShortName(from.getAbbreviation());
+		to.setActive(!from.isClosed());
+		if (from.getAuthor() != null) {
+			to.setPpAuthorName(from.getAuthor().getName());
+			to.setPpAuthorMail(from.getAuthor().getMail());
+			to.setPpUniversity(from.getAuthor().getOrganizationName());
+			to.setPpFaculty(from.getAuthor().getOrganizationUnit());
+			to.setPpLogo(from.getAuthor().getOrganizationLogo());
+		}
+		to.setFeatures(migrate(from.getSettings()));
+
+		return to;
+	}
+
+	public Room migrate(final de.thm.arsnova.model.Room from) {
+		return migrate(from, Optional.empty());
+	}
+
+	public RoomFeature migrate(final de.thm.arsnova.model.Room.Settings settings) {
+		final RoomFeature feature = new RoomFeature();
+
+		/* Features */
+		feature.setInterposed(settings.isCommentsEnabled());
+		feature.setLecture(settings.isQuestionsEnabled());
+		feature.setJitt(settings.isQuestionsEnabled());
+		feature.setSlides(settings.isSlidesEnabled());
+		feature.setFlashcardFeature(settings.isFlashcardsEnabled());
+		feature.setFeedback(settings.isQuickFeedbackEnabled());
+		feature.setPi(settings.isMultipleRoundsEnabled() || settings.isTimerEnabled());
+		feature.setLearningProgress(settings.isScoreEnabled());
+
+		/* Use cases */
+		int count = 0;
+		/* Single-feature use cases can be migrated */
+		if (settings.isCommentsEnabled()) {
+			feature.setInterposedFeedback(true);
+			count++;
+		}
+		if (settings.isFlashcardsEnabled()) {
+			feature.setFlashcard(true);
+			count++;
+		}
+		if (settings.isQuickFeedbackEnabled()) {
+			feature.setLiveFeedback(true);
+			count++;
+		}
+		if (settings.isQuickSurveyEnabled()) {
+			feature.setLiveClicker(true);
+			count++;
+		}
+		/* For the following features an exact migration is not possible, so custom is set */
+		if (settings.isQuestionsEnabled()) {
+			feature.setCustom(true);
+			count++;
+		}
+		if (settings.isSlidesEnabled()) {
+			feature.setCustom(true);
+			count++;
+		}
+		if (settings.isMultipleRoundsEnabled() || settings.isTimerEnabled()) {
+			feature.setCustom(true);
+			count++;
+		}
+		if (settings.isScoreEnabled()) {
+			feature.setCustom(true);
+			count++;
+		}
+
+		if (count != 1) {
+			/* Reset single-feature use-cases since multiple features were detected */
+			feature.setInterposedFeedback(false);
+			feature.setFlashcard(false);
+			feature.setLiveFeedback(false);
+			feature.setLiveClicker(false);
+
+			if (count == 7) {
+				feature.setCustom(false);
+				feature.setTotal(true);
+			} else {
+				feature.setCustom(true);
+			}
+		}
+
+		return feature;
+	}
+
+	public Content migrate(final de.thm.arsnova.model.Content from) {
+		final Content to = new Content();
+		copyCommonProperties(from, to);
+		to.setSessionId(from.getRoomId());
+		to.setSubject(from.getSubject());
+		to.setText(from.getBody());
+		to.setAbstention(from.isAbstentionsAllowed());
+		if (!from.getState().isAdditionalTextVisible() || "Solution".equals(from.getAdditionalTextTitle())) {
+			to.setSolution(from.getAdditionalText());
+		} else if (from.getAdditionalText() != null) {
+			to.setHint(from.getAdditionalText());
+		}
+
+		if (from instanceof ChoiceQuestionContent) {
+			final ChoiceQuestionContent fromChoiceQuestionContent = (ChoiceQuestionContent) from;
+			switch (from.getFormat()) {
+				case CHOICE:
+					to.setQuestionType(fromChoiceQuestionContent.isMultiple() ? V2_TYPE_MC : V2_TYPE_ABCD);
+					break;
+				case BINARY:
+					to.setQuestionType(V2_TYPE_YESNO);
+					break;
+				case SCALE:
+					final int optionCount = fromChoiceQuestionContent.getOptions().size();
+					/* The number of options for vote/school format is hard-coded by the legacy client */
+					if (optionCount == 5) {
+						to.setQuestionType(V2_TYPE_VOTE);
+					} else if (optionCount == 6) {
+						to.setQuestionType(V2_TYPE_SCHOOL);
+					} else {
+						to.setQuestionType(V2_TYPE_ABCD);
+					}
+					break;
+				case GRID:
+					to.setQuestionType(V2_TYPE_GRID);
+					break;
+				default:
+					throw new IllegalArgumentException("Unsupported content format.");
+			}
+			final List<AnswerOption> toOptions = new ArrayList<>();
+			to.setPossibleAnswers(toOptions);
+			for (int i = 0; i < fromChoiceQuestionContent.getOptions().size(); i++) {
+				final AnswerOption option = new AnswerOption();
+				option.setText(fromChoiceQuestionContent.getOptions().get(i).getLabel());
+				option.setValue(fromChoiceQuestionContent.getOptions().get(i).getPoints());
+				option.setCorrect(fromChoiceQuestionContent.getCorrectOptionIndexes().contains(i));
+				toOptions.add(option);
+			}
+		} else {
+			switch (from.getFormat()) {
+				case NUMBER:
+					to.setQuestionType(V2_TYPE_FREETEXT);
+					break;
+				case TEXT:
+					final String legacyType = from.getExtensions() != null
+							? (String) from.getExtensions()
+								.getOrDefault("v2", Collections.emptyMap()).getOrDefault("format", "")
+							: "";
+					switch (legacyType) {
+						case V2_TYPE_SLIDE:
+							to.setQuestionType(V2_TYPE_SLIDE);
+							break;
+						case V2_TYPE_FLASHCARD:
+							to.setQuestionType(V2_TYPE_FLASHCARD);
+							final AnswerOption back = new AnswerOption();
+							back.setText(from.getAdditionalText());
+							back.setCorrect(true);
+							to.setPossibleAnswers(Collections.singletonList(back));
+
+							break;
+						default:
+							to.setQuestionType(V2_TYPE_FREETEXT);
+							break;
+					}
+					break;
+				case GRID:
+					final GridImageContent fromGridImageContent = (GridImageContent) from;
+					final GridImageContent.Grid grid = fromGridImageContent.getGrid();
+					final GridImageContent.Image image = fromGridImageContent.getImage();
+					to.setQuestionType(V2_TYPE_GRID);
+					to.setGridSizeX(grid.getColumns());
+					to.setGridSizeY(grid.getRows());
+					to.setGridOffsetX((int) (Math.round(grid.getNormalizedX() * V2_GRID_CONTAINER_SIZE)));
+					to.setGridOffsetY((int) (Math.round(grid.getNormalizedY() * V2_GRID_CONTAINER_SIZE)));
+					/* v3 normalized field size = v2 scale factor ^ v2 zoom level / v2 grid size */
+					to.setGridSize(V2_GRID_FIELD_COUNT);
+					to.setGridScaleFactor(String.valueOf(V2_GRID_SCALE_FACTOR));
+					to.setGridZoomLvl((int) Math.round(
+							Math.log(grid.getNormalizedFieldSize() * V2_GRID_FIELD_COUNT)
+								/ Math.log(V2_GRID_SCALE_FACTOR)));
+					to.setGridIsHidden(!grid.isVisible());
+					to.setImage(image.getUrl());
+					to.setImgRotation(image.getRotation() / 90 % 4);
+					to.setScaleFactor(String.valueOf(V2_GRID_SCALE_FACTOR));
+					to.setZoomLvl((int) Math.round(
+							Math.log(image.getScaleFactor()) / Math.log(V2_GRID_SCALE_FACTOR)));
+					to.setPossibleAnswers(
+							fromGridImageContent.getCorrectOptionIndexes().stream()
+									.map(i -> {
+										final int x = i % fromGridImageContent.getGrid().getColumns();
+										final int y = i / fromGridImageContent.getGrid().getColumns();
+										final AnswerOption answerOption = new AnswerOption();
+										answerOption.setText(x + ";" + y);
+										answerOption.setCorrect(true);
+
+										return answerOption;
+									})
+									.collect(Collectors.toList()));
+					if (fromGridImageContent.getExtensions() != null) {
+						final Map<String, Object> v2 = fromGridImageContent.getExtensions()
+								.getOrDefault(V2, Collections.emptyMap());
+						to.setGridType((String) v2.getOrDefault(V2_GRID_TYPE, V2_GRID_DEFAULT_TYPE));
+						to.setOffsetX((int) v2.getOrDefault(V2_GRID_IMAGE_ABSOLUTE_X, 0));
+						to.setOffsetY((int) v2.getOrDefault(V2_GRID_IMAGE_ABSOLUTE_Y, 0));
+						to.setNumberOfDots((int) v2.getOrDefault(V2_GRID_MODERATION_DOT_LIMIT, 0));
+					} else {
+						to.setGridType(V2_GRID_DEFAULT_TYPE);
+					}
+
+					break;
+				default:
+					throw new IllegalArgumentException("Unsupported content format.");
+			}
+		}
+		final de.thm.arsnova.model.Content.State state = from.getState();
+		to.setPiRound(state.getRound());
+		to.setActive(state.isVisible());
+		to.setShowStatistic(state.isResponsesVisible());
+		to.setShowAnswer(state.isAdditionalTextVisible());
+		to.setVotingDisabled(!state.isResponsesEnabled());
+		if (from.getGroups().size() == 1) {
+			to.setQuestionVariant(from.getGroups().iterator().next());
+		}
+
+		return to;
+	}
+
+	public Answer migrate(final de.thm.arsnova.model.ChoiceAnswer from,
+			final de.thm.arsnova.model.Content content, final Optional<UserProfile> creator) {
+		final Answer to = new Answer();
+		copyCommonProperties(from, to);
+		to.setQuestionId(from.getContentId());
+		to.setSessionId(from.getRoomId());
+		to.setPiRound(from.getRound());
+		if (creator.isPresent()) {
+			to.setUser(creator.get().getLoginId());
+		}
+		if (from.getSelectedChoiceIndexes().isEmpty()) {
+			to.setAbstention(true);
+		} else {
+			if (content instanceof ChoiceQuestionContent) {
+				final ChoiceQuestionContent choiceQuestionContent = (ChoiceQuestionContent) content;
+				if (choiceQuestionContent.isMultiple()) {
+					to.setAnswerText(migrateChoice(from.getSelectedChoiceIndexes(),
+							choiceQuestionContent.getOptions()));
+				} else {
+					final int index = from.getSelectedChoiceIndexes().get(0);
+					to.setAnswerText(choiceQuestionContent.getOptions().get(index).getLabel());
+				}
+			} else if (content instanceof GridImageContent) {
+				final GridImageContent gridImageContent = (GridImageContent) content;
+				to.setAnswerText(migrateChoice(from.getSelectedChoiceIndexes(), gridImageContent.getGrid()));
+			} else {
+				throw new IllegalArgumentException(
+						"Content expected to be an instance of ChoiceQuestionContent or GridImageContent");
+			}
+		}
+
+		return to;
+	}
+
+	public Answer migrate(final de.thm.arsnova.model.ChoiceAnswer from,
+			final de.thm.arsnova.model.Content content) {
+		return migrate(from, content, Optional.empty());
+	}
+
+	public Answer migrate(final de.thm.arsnova.model.TextAnswer from,
+			final Optional<de.thm.arsnova.model.Content> content, final Optional<UserProfile> creator) {
+		final Answer to = new Answer();
+		copyCommonProperties(from, to);
+		to.setQuestionId(from.getContentId());
+		to.setSessionId(from.getRoomId());
+		to.setPiRound(from.getRound());
+		if (creator.isPresent()) {
+			to.setUser(creator.get().getLoginId());
+		}
+
+		to.setAnswerSubject(from.getSubject());
+		to.setAnswerText(from.getBody());
+
+		return to;
+	}
+
+	public Answer migrate(final de.thm.arsnova.model.TextAnswer from) {
+		return migrate(from, Optional.empty(), Optional.empty());
+	}
+
+	public Comment migrate(final de.thm.arsnova.model.Comment from, final Optional<UserProfile> creator) {
+		final Comment to = new Comment();
+		copyCommonProperties(from, to);
+		to.setSessionId(from.getRoomId());
+		if (creator.isPresent()) {
+			to.setCreator(creator.get().getLoginId());
+		}
+		to.setSubject(from.getSubject());
+		to.setText(from.getBody());
+		to.setTimestamp(from.getTimestamp().getTime());
+		to.setRead(from.isRead());
+
+		return to;
+	}
+
+	public Comment migrate(final de.thm.arsnova.model.Comment from) {
+		return migrate(from, Optional.empty());
+	}
+
+	public Motd migrate(final de.thm.arsnova.model.Motd from) {
+		final Motd to = new Motd();
+		copyCommonProperties(from, to);
+		to.setMotdkey(from.getId());
+		to.setStartdate(from.getCreationTimestamp());
+		to.setStartdate(from.getStartDate());
+		to.setEnddate(from.getEndDate());
+		switch (from.getAudience()) {
+			case ALL:
+				to.setAudience("all");
+				break;
+			case AUTHORS:
+				to.setAudience("tutors");
+				break;
+			case PARTICIPANTS:
+				to.setAudience("students");
+				break;
+			case ROOM:
+				to.setAudience("session");
+				break;
+			default:
+				break;
+		}
+		to.setTitle(from.getTitle());
+		to.setText(from.getBody());
+		to.setSessionId(from.getRoomId());
+
+		return to;
+	}
+
+	public List<Answer> migrate(final AnswerStatistics from,
+			final de.thm.arsnova.model.Content content, final int round) {
+		if (round < 1 || round > content.getState().getRound()) {
+			throw new IllegalArgumentException("Invalid value for round");
+		}
+		final List<Answer> to  = new ArrayList<>();
+		final AnswerStatistics.RoundStatistics stats = from.getRoundStatistics().get(round - 1);
+
+		if (content.isAbstentionsAllowed()) {
+			final Answer abstention = new Answer();
+			abstention.setQuestionId(content.getId());
+			abstention.setPiRound(round);
+			abstention.setAnswerCount(stats.getAbstentionCount());
+			abstention.setAbstentionCount(stats.getAbstentionCount());
+			to.add(abstention);
+		}
+
+		final Map<String, Integer> choices;
+		if (content instanceof ChoiceQuestionContent) {
+			final ChoiceQuestionContent choiceQuestionContent = (ChoiceQuestionContent) content;
+			if (choiceQuestionContent.isMultiple()) {
+				/* Map selected choice indexes -> answer count */
+				choices = stats.getCombinatedCounts().stream().collect(Collectors.toMap(
+						c -> migrateChoice(c.getSelectedChoiceIndexes(), choiceQuestionContent.getOptions()),
+						c -> c.getCount(),
+						(u, v) -> {
+							throw new IllegalStateException(String.format("Duplicate key %s", u));
+						},
+						LinkedHashMap::new));
+			} else {
+				choices = new LinkedHashMap<>();
+				int i = 0;
+				for (final ChoiceQuestionContent.AnswerOption option : choiceQuestionContent.getOptions()) {
+					choices.put(option.getLabel(), stats.getIndependentCounts().get(i));
+					i++;
+				}
+			}
+		} else {
+			final GridImageContent gridImageContent = (GridImageContent) content;
+			choices = stats.getCombinatedCounts().stream().collect(Collectors.toMap(
+					c -> migrateChoice(c.getSelectedChoiceIndexes(), gridImageContent.getGrid()),
+					c -> c.getCount(),
+					(u, v) -> {
+						throw new IllegalStateException(String.format("Duplicate key %s", u));
+					},
+					LinkedHashMap::new));
+		}
+
+		for (final Map.Entry<String, Integer> choice : choices.entrySet()) {
+			final Answer answer = new Answer();
+			answer.setQuestionId(content.getId());
+			answer.setPiRound(round);
+			answer.setAnswerCount(choice.getValue());
+			answer.setAbstentionCount(stats.getAbstentionCount());
+			answer.setAnswerText(choice.getKey());
+			to.add(answer);
+		}
+
+		return to;
+	}
+
+	public LoggedIn migrateLoggedIn(final UserProfile from) {
+		final LoggedIn to = new LoggedIn();
+		copyCommonProperties(from, to);
+		to.setUser(from.getLoginId());
+		to.setTimestamp(from.getLastLoginTimestamp().getTime());
+		to.setVisitedSessions(from.getRoomHistory().stream()
+				.map(entry -> new VisitedRoom())
+				.collect(Collectors.toList()));
+
+		return to;
+	}
+
+	public MotdList migrateMotdList(final UserProfile from) {
+		final MotdList to = new MotdList();
+		copyCommonProperties(from, to);
+		to.setUsername(from.getLoginId());
+		to.setMotdkeys(String.join(",", from.getAcknowledgedMotds()));
+
+		return to;
+	}
+
+	public RoomInfo migrateStats(final de.thm.arsnova.model.Room from) {
+		final RoomInfo to = new RoomInfo(migrate(from));
+		final RoomStatistics stats = from.getStatistics();
+		to.setNumQuestions(stats.getContentCount());
+		to.setNumUnanswered(stats.getUnansweredContentCount());
+		to.setNumAnswers(stats.getAnswerCount());
+		to.setNumInterposed(stats.getCommentCount());
+		to.setNumUnredInterposed(stats.getUnreadCommentCount());
+
+		return to;
+	}
+
+	private String migrateChoice(final List<Integer> selectedChoiceIndexes,
+			final List<ChoiceQuestionContent.AnswerOption> options) {
+		final List<String> answers = new ArrayList<>();
+		for (int i = 0; i < options.size(); i++) {
+			answers.add(selectedChoiceIndexes.contains(i) ? "1" : "0");
+		}
+
+		return answers.stream().collect(Collectors.joining(","));
+	}
+
+	private String migrateChoice(final List<Integer> selectedChoiceIndexes, final GridImageContent.Grid grid) {
+		return selectedChoiceIndexes.stream()
+				.map(i -> {
+					final int x = i % grid.getColumns();
+					final int y = i / grid.getColumns();
+					return x + ";" + y;
+				})
+				.collect(Collectors.joining(","));
+	}
+}

src/main/java/de/thm/arsnova/entities/Answer.java → src/main/java/de/thm/arsnova/model/migration/v2/Answer.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,116 +15,204 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
+
+package de.thm.arsnova.model.migration.v2;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
 
-public class Answer {
+import de.thm.arsnova.model.serialization.View;
 
-	private String _id;
-	private String _rev;
+/**
+ * Both a regular (single choice, evaluation, etc.) as well as a freetext answer.
+ *
+ * <p>
+ * This class has additional fields to transport generated answer statistics.
+ * </p>
+ */
+@ApiModel(value = "Answer", description = "Answer entity - Can represent a single answer or summarized statistics")
+public class Answer implements Entity {
+	private String id;
+	private String rev;
 	private String type;
 	private String sessionId;
 	private String questionId;
 	private String answerText;
+	private String answerTextRaw;
 	private String answerSubject;
+	private boolean successfulFreeTextAnswer;
 	private String questionVariant;
 	private int questionValue;
 	private int piRound;
 	private String user;
 	private long timestamp;
+	private boolean read;
 	private int answerCount = 1;
 	private boolean abstention;
 	private int abstentionCount;
+	@JsonIgnore
+	private String answerImage;
+	private String answerThumbnailImage;
 
 	public Answer() {
 		this.type = "skill_question_answer";
 	}
 
-	public final String get_id() {
-		return _id;
-	}
-
-	public final void set_id(String _id) {
-		this._id = _id;
-	}
-
-	public final String get_rev() {
-		return _rev;
+	@ApiModelProperty(required = true, value = "the couchDB ID")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getId() {
+		return id;
 	}
 
-	public final void set_rev(final String _rev) {
-		this._rev = _rev;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
 	}
 
-	public final String getType() {
-		return type;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRevision(final String rev) {
+		this.rev = rev;
 	}
 
-	public final void setType(final String type) {
-		this.type = type;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getRevision() {
+		return rev;
 	}
 
+	@ApiModelProperty(required = true, value = "ID of the session, the answer is assigned to")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getSessionId() {
 		return sessionId;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setSessionId(final String sessionId) {
 		this.sessionId = sessionId;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display question id")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getQuestionId() {
 		return questionId;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setQuestionId(final String questionId) {
 		this.questionId = questionId;
 	}
 
+	@ApiModelProperty(required = true, value = "the answer text")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getAnswerText() {
 		return answerText;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setAnswerText(final String answerText) {
 		this.answerText = answerText;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final String getAnswerTextRaw() {
+		return this.answerTextRaw;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final void setAnswerTextRaw(final String answerTextRaw) {
+		this.answerTextRaw = answerTextRaw;
+	}
+
+	@ApiModelProperty(required = true, value = "the answer subject")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getAnswerSubject() {
 		return answerSubject;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setAnswerSubject(final String answerSubject) {
 		this.answerSubject = answerSubject;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final boolean isSuccessfulFreeTextAnswer() {
+		return this.successfulFreeTextAnswer;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final void setSuccessfulFreeTextAnswer(final boolean successfulFreeTextAnswer) {
+		this.successfulFreeTextAnswer = successfulFreeTextAnswer;
+	}
+
+	@ApiModelProperty(required = true, value = "the peer instruction round nr.")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getPiRound() {
 		return piRound;
 	}
 
-	public void setPiRound(int piRound) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setPiRound(final int piRound) {
 		this.piRound = piRound;
 	}
 
-	/* TODO: use JsonViews instead of JsonIgnore when supported by Spring (4.1)
-	 * http://wiki.fasterxml.com/JacksonJsonViews
-	 * https://jira.spring.io/browse/SPR-7156 */
-	@JsonIgnore
+	@ApiModelProperty(required = true, value = "the user")
+	@JsonView(View.Persistence.class)
 	public final String getUser() {
 		return user;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setUser(final String user) {
 		this.user = user;
 	}
 
+	@ApiModelProperty(required = true, value = "the answer image")
+	@JsonView(View.Persistence.class)
+	public String getAnswerImage() {
+		return answerImage;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setAnswerImage(final String answerImage) {
+		this.answerImage = answerImage;
+	}
+
+	@ApiModelProperty(required = true, value = "the answer thumbnail")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getAnswerThumbnailImage() {
+		return answerThumbnailImage;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setAnswerThumbnailImage(final String answerThumbnailImage) {
+		this.answerThumbnailImage = answerThumbnailImage;
+	}
+
+	@ApiModelProperty(required = true, value = "the creation date timestamp")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public long getTimestamp() {
 		return timestamp;
 	}
 
-	public void setTimestamp(long timestamp) {
+	@JsonView(View.Persistence.class)
+	public void setTimestamp(final long timestamp) {
 		this.timestamp = timestamp;
 	}
 
+	@ApiModelProperty(required = true, value = "displays whether the answer is read")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isRead() {
+		return read;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRead(final boolean read) {
+		this.read = read;
+	}
+
+	@ApiModelProperty(required = true, value = "the number of answers given. used for statistics")
+	@JsonView(View.Public.class)
 	public final int getAnswerCount() {
 		return answerCount;
 	}
@@ -133,35 +221,46 @@ public class Answer {
 		this.answerCount = answerCount;
 	}
 
+	@ApiModelProperty(required = true, value = "the abstention")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isAbstention() {
 		return abstention;
 	}
 
-	public void setAbstention(boolean abstention) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setAbstention(final boolean abstention) {
 		this.abstention = abstention;
 	}
 
+	@ApiModelProperty(required = true, value = "the number of abstentions given. used for statistics")
+	@JsonView(View.Public.class)
 	public int getAbstentionCount() {
 		return abstentionCount;
 	}
 
-	public void setAbstentionCount(int abstentionCount) {
+	public void setAbstentionCount(final int abstentionCount) {
 		this.abstentionCount = abstentionCount;
 	}
 
+	@ApiModelProperty(required = true, value = "either lecture or preparation")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getQuestionVariant() {
 		return questionVariant;
 	}
 
-	public void setQuestionVariant(String questionVariant) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setQuestionVariant(final String questionVariant) {
 		this.questionVariant = questionVariant;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display question value")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getQuestionValue() {
 		return questionValue;
 	}
 
-	public void setQuestionValue(int questionValue) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setQuestionValue(final int questionValue) {
 		this.questionValue = questionValue;
 	}
 
@@ -181,8 +280,8 @@ public class Answer {
 		// auto generated!
 		final int prime = 31;
 		int result = 1;
-		result = prime * result + ((_id == null) ? 0 : _id.hashCode());
-		result = prime * result + ((_rev == null) ? 0 : _rev.hashCode());
+		result = prime * result + ((id == null) ? 0 : id.hashCode());
+		result = prime * result + ((rev == null) ? 0 : rev.hashCode());
 		result = prime * result + ((answerSubject == null) ? 0 : answerSubject.hashCode());
 		result = prime * result + ((answerText == null) ? 0 : answerText.hashCode());
 		result = prime * result + piRound;
@@ -194,26 +293,30 @@ public class Answer {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(final Object obj) {
 		// auto generated!
-		if (this == obj) return true;
-		if (obj == null) return false;
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null) {
+			return false;
+		}
 		if (getClass() != obj.getClass()) {
 			return false;
 		}
-		Answer other = (Answer) obj;
-		if (_id == null) {
-			if (other._id != null) {
+		final Answer other = (Answer) obj;
+		if (id == null) {
+			if (other.id != null) {
 				return false;
 			}
-		} else if (!_id.equals(other._id)) {
+		} else if (!id.equals(other.id)) {
 			return false;
 		}
-		if (_rev == null) {
-			if (other._rev != null) {
+		if (rev == null) {
+			if (other.rev != null) {
 				return false;
 			}
-		} else if (!_rev.equals(other._rev)) {
+		} else if (!rev.equals(other.rev)) {
 			return false;
 		}
 		if (answerSubject == null) {

src/main/java/de/thm/arsnova/model/migration/v2/AnswerOption.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+import java.io.Serializable;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * Represents an Answer (Possible Answer) of Content.
+ */
+@ApiModel(value = "AnswerOption", description = "Answer Option (Possible Answer) entity")
+public class AnswerOption implements Serializable {
+
+	private String id;
+	private String text;
+	private boolean correct;
+	private int value;
+
+	@ApiModelProperty(required = true, value = "the ID")
+	public String getId() {
+		return this.id;
+	}
+
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@ApiModelProperty(required = true, value = "the text")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getText() {
+		return text;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setText(final String text) {
+		this.text = text;
+	}
+
+	@ApiModelProperty(required = true, value = "true for a correct answer")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isCorrect() {
+		return correct;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setCorrect(final boolean correct) {
+		this.correct = correct;
+	}
+
+	@ApiModelProperty(required = true, value = "the value")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public int getValue() {
+		return value;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setValue(final int value) {
+		this.value = value;
+	}
+
+	@Override
+	public String toString() {
+		return "AnswerOption [id=" + id + ", text=" + text + ", correct=" + correct + "]";
+	}
+}

src/main/java/de/thm/arsnova/entities/User.java → src/main/java/de/thm/arsnova/model/migration/v2/ClientAuthentication.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,95 +15,96 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
-import java.io.Serializable;
+package de.thm.arsnova.model.migration.v2;
 
-import org.jasig.cas.client.authentication.AttributePrincipal;
-import org.scribe.up.profile.facebook.FacebookProfile;
-import org.scribe.up.profile.google.Google2Profile;
-import org.scribe.up.profile.twitter.TwitterProfile;
+import com.fasterxml.jackson.annotation.JsonView;
+import java.io.Serializable;
+import java.util.Objects;
 import org.springframework.security.authentication.AnonymousAuthenticationToken;
-import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.Authentication;
 
-import de.thm.arsnova.services.UserSessionService;
+import de.thm.arsnova.model.UserProfile;
+import de.thm.arsnova.model.serialization.View;
+import de.thm.arsnova.security.User;
 
-public class User implements Serializable {
-	public static final String GOOGLE = "google";
-	public static final String TWITTER = "twitter";
-	public static final String FACEBOOK = "facebook";
-	public static final String THM = "thm";
-	public static final String LDAP = "ldap";
-	public static final String ARSNOVA = "arsnova";
+/**
+ * Represents a user.
+ */
+public class ClientAuthentication implements Serializable {
 	public static final String ANONYMOUS = "anonymous";
-	public static final String GUEST = "guest";
 
 	private static final long serialVersionUID = 1L;
+	private String id;
 	private String username;
-	private String type;
-	private UserSessionService.Role role;
-
-	public User(Google2Profile profile) {
-		setUsername(profile.getEmail());
-		setType(User.GOOGLE);
-	}
-
-	public User(TwitterProfile profile) {
-		setUsername(profile.getScreenName());
-		setType(User.TWITTER);
-	}
-
-	public User(FacebookProfile profile) {
-		setUsername(profile.getLink());
-		setType(User.FACEBOOK);
-	}
-
-	public User(AttributePrincipal principal) {
-		setUsername(principal.getName());
-		setType(User.THM);
+	private UserProfile.AuthProvider authProvider;
+	private boolean isAdmin;
+
+	public ClientAuthentication() {
+		username = ANONYMOUS;
+		authProvider = UserProfile.AuthProvider.NONE;
+	}
+
+	public ClientAuthentication(final User user) {
+		id = user.getId();
+		username = user.getUsername();
+		authProvider = user.getAuthProvider();
+		isAdmin = user.isAdmin();
+	}
+
+	public ClientAuthentication(final Authentication authentication) {
+		if (authentication instanceof AnonymousAuthenticationToken) {
+			setUsername(ClientAuthentication.ANONYMOUS);
+		} else {
+			if (!(authentication.getPrincipal() instanceof User)) {
+				throw new IllegalArgumentException("Unsupported authentication token");
+			}
+			final User user = (User) authentication.getPrincipal();
+			id = user.getId();
+			username = user.getUsername();
+			authProvider = user.getAuthProvider();
+			isAdmin = user.isAdmin();
+		}
 	}
 
-	public User(AnonymousAuthenticationToken token) {
-		setUsername(User.ANONYMOUS);
-		setType(User.ANONYMOUS);
+	public String getId() {
+		return id;
 	}
 
-	public User(UsernamePasswordAuthenticationToken token) {
-		setUsername(token.getName());
-		setType(LDAP);
+	public void setId(final String id) {
+		this.id = id;
 	}
 
+	@JsonView(View.Public.class)
 	public String getUsername() {
 		return username;
 	}
 
-	public void setUsername(String username) {
+	public void setUsername(final String username) {
 		this.username = username;
 	}
 
-	public String getType() {
-		return type;
+	@JsonView(View.Public.class)
+	public UserProfile.AuthProvider getAuthProvider() {
+		return authProvider;
 	}
 
-	public void setType(String type) {
-		this.type = type;
+	public void setAuthProvider(final UserProfile.AuthProvider authProvider) {
+		this.authProvider = authProvider;
 	}
 
-	public UserSessionService.Role getRole() {
-		return role;
+	public void setAdmin(final boolean a) {
+		this.isAdmin = a;
 	}
 
-	public void setRole(UserSessionService.Role role) {
-		this.role = role;
-	}
-
-	public boolean hasRole(UserSessionService.Role role) {
-		return this.role == role;
+	@JsonView(View.Public.class)
+	public boolean isAdmin() {
+		return this.isAdmin;
 	}
 
 	@Override
 	public String toString() {
-		return "User [username=" + username + ", type=" + type + "]";
+		return "User [username=" + username + ", authProvider=" + authProvider + "]";
 	}
 
 	@Override
@@ -114,16 +115,18 @@ public class User implements Serializable {
 
 		int result = theAnswer;
 		result = theOthers * result + this.username.hashCode();
-		return theOthers * result + this.type.hashCode();
+		return theOthers * result + this.authProvider.hashCode();
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(final Object obj) {
 		if (obj == null || !obj.getClass().equals(this.getClass())) {
 			return false;
 		}
-		User other = (User) obj;
-		return this.username.equals(other.username) && this.type.equals(other.type);
+		final ClientAuthentication other = (ClientAuthentication) obj;
+
+		return this.authProvider == other.authProvider
+				&& Objects.equals(this.id, other.id) && this.username.equals(other.username);
 	}
 
 }

src/main/java/de/thm/arsnova/entities/InterposedQuestion.java → src/main/java/de/thm/arsnova/model/migration/v2/Comment.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,15 +15,23 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
-import com.fasterxml.jackson.annotation.JsonIgnore;
+package de.thm.arsnova.model.migration.v2;
 
-public class InterposedQuestion {
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
 
-	private String _id;
-	private String _rev;
-	private String type;
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * A Comment (Interposed/Feedback/Audience question) from a attendee in a Room.
+ */
+@ApiModel(value = "Comment", description = "Comment (Interposed/Feedback/Audience Question) entity")
+public class Comment implements Entity {
+	private String id;
+	private String rev;
 	private String subject;
 	private String text;
 	/* FIXME sessionId actually is used to hold the sessionKey.
@@ -36,68 +44,100 @@ public class InterposedQuestion {
 	private boolean read;
 	private String creator;
 
-	public String get_id() {
-		return _id;
+	@JsonView({View.Persistence.class, View.Public.class})
+	@JsonProperty("_id")
+	public String getId() {
+		return id;
 	}
-	public void set_id(String _id) {
-		this._id = _id;
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRevision(final String rev) {
+		this.rev = rev;
 	}
-	public String get_rev() {
-		return _rev;
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getRevision() {
+		return rev;
 	}
-	public void set_rev(String _rev) {
-		this._rev = _rev;
+
+	/* Need because of an inconsistency in the v2 API */
+	@JsonView(View.Public.class)
+	@JsonProperty("id")
+	public String getApiId() {
+		return id;
 	}
+
+	@ApiModelProperty(required = true, value = "is read")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isRead() {
 		return read;
 	}
-	public void setRead(boolean read) {
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRead(final boolean read) {
 		this.read = read;
 	}
-	public String getType() {
-		return type;
-	}
-	public void setType(String type) {
-		this.type = type;
-	}
+
+	@ApiModelProperty(required = true, value = "the subject")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getSubject() {
 		return subject;
 	}
-	public void setSubject(String subject) {
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setSubject(final String subject) {
 		this.subject = subject;
 	}
+
+	@ApiModelProperty(required = true, value = "the Text")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getText() {
 		return text;
 	}
-	public void setText(String text) {
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setText(final String text) {
 		this.text = text;
 	}
+
+	@ApiModelProperty(required = true, value = "ID of the session, the comment is assigned to")
+	@JsonView(View.Persistence.class)
 	public String getSessionId() {
 		return sessionId;
 	}
-	public void setSessionId(String sessionId) {
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setSessionId(final String sessionId) {
 		this.sessionId = sessionId;
 	}
+
+	@ApiModelProperty(required = true, value = "creation date timestamp")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public long getTimestamp() {
 		return timestamp;
 	}
-	public void setTimestamp(long timestamp) {
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setTimestamp(final long timestamp) {
 		this.timestamp = timestamp;
 	}
 
-	/* TODO: use JsonViews instead of JsonIgnore when supported by Spring (4.1)
-	 * http://wiki.fasterxml.com/JacksonJsonViews
-	 * https://jira.spring.io/browse/SPR-7156 */
-	@JsonIgnore
+	@JsonView(View.Persistence.class)
 	public String getCreator() {
 		return creator;
 	}
 
-	public void setCreator(String creator) {
+	@JsonView(View.Persistence.class)
+	public void setCreator(final String creator) {
 		this.creator = creator;
 	}
 
-	public boolean isCreator(User user) {
+	public boolean isCreator(final ClientAuthentication user) {
 		return user.getUsername().equals(creator);
 	}
 }

src/main/java/de/thm/arsnova/model/migration/v2/CommentReadingCount.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * Wrapper class for counting read and unread Comments for a Room or a single user.
+ */
+@ApiModel(value = "Comment Reading Count", description = "Comment Reading Count statistics entity")
+public class CommentReadingCount {
+
+	private int read;
+	private int unread;
+
+	public CommentReadingCount(final int readCount, final int unreadCount) {
+		this.read = readCount;
+		this.unread = unreadCount;
+	}
+
+	public CommentReadingCount() {
+		this.read = 0;
+		this.unread = 0;
+	}
+
+	@ApiModelProperty(required = true, value = "the number of read comments")
+	@JsonView(View.Public.class)
+	public int getRead() {
+		return read;
+	}
+
+	public void setRead(final int read) {
+		this.read = read;
+	}
+
+	@ApiModelProperty(required = true, value = "the number of unread comments")
+	@JsonView(View.Public.class)
+	public int getUnread() {
+		return unread;
+	}
+
+	public void setUnread(final int unread) {
+		this.unread = unread;
+	}
+
+	@ApiModelProperty(required = true, value = "the number of total comments")
+	@JsonView(View.Public.class)
+	public int getTotal() {
+		return getRead() + getUnread();
+	}
+}

src/main/java/de/thm/arsnova/entities/Question.java → src/main/java/de/thm/arsnova/model/migration/v2/Content.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,21 +15,32 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
-import java.util.HashMap;
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+import java.util.ArrayList;
+import java.util.Date;
 import java.util.List;
 
-public class Question {
+import de.thm.arsnova.model.serialization.View;
 
-	private String type;
+/**
+ * Represents Content (Skill/Lecturer Question) in a Room.
+ */
+@ApiModel(value = "Content", description = "Content (Skill/Lecturer Question) entity")
+public class Content implements Entity {
+	private String id;
+	private String rev;
 	private String questionType;
 	private String questionVariant;
 	private String subject;
 	private String text;
 	private boolean active;
 	private String releasedFor;
-	private List<PossibleAnswer> possibleAnswers;
+	private List<AnswerOption> possibleAnswers;
 	private boolean noCorrect;
 	// TODO: We currently need both sessionId and sessionKeyword, but sessionKeyword will not be persisted.
 	private String sessionId;
@@ -39,14 +50,21 @@ public class Question {
 	private int number;
 	private int duration;
 	private int piRound;
-	private long piRoundEndTime;
-	private long piRoundStartTime;
-	private boolean piRoundActive;
+	private long piRoundEndTime = 0;
+	private long piRoundStartTime = 0;
+	private boolean piRoundFinished = false;
+	private boolean piRoundActive = false;
+	private boolean votingDisabled;
 	private boolean showStatistic; // sic
 	private boolean showAnswer;
 	private boolean abstention;
-	private String _id;
-	private String _rev;
+	private boolean ignoreCaseSensitive;
+	private boolean ignoreWhitespaces;
+	private boolean ignorePunctuation;
+	private boolean fixedAnswer;
+	private boolean strictMode;
+	private int rating;
+	private String correctAnswer;
 
 	private String image;
 	private String fcImage;
@@ -70,55 +88,88 @@ public class Question {
 	private String gridType;
 	private String scaleFactor;
 	private String gridScaleFactor;
+	private boolean imageQuestion;
+	private boolean textAnswerEnabled;
+	private String hint;
+	private String solution;
+
+	@ApiModelProperty(required = true, value = "the couchDB ID")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getId() {
+		return id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
+	}
 
-	public final String getType() {
-		return type;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRevision(final String rev) {
+		this.rev = rev;
 	}
 
-	public final void setType(final String type) {
-		this.type = type;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getRevision() {
+		return rev;
 	}
 
+	@ApiModelProperty(required = true, value = "the question type")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getQuestionType() {
 		return questionType;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setQuestionType(final String questionType) {
 		this.questionType = questionType;
 	}
 
+	@ApiModelProperty(required = true, value = "either lecture or preparation")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getQuestionVariant() {
 		return questionVariant;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setQuestionVariant(final String questionVariant) {
 		this.questionVariant = questionVariant;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display subject")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getSubject() {
 		return subject;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setSubject(final String subject) {
 		this.subject = subject;
 	}
 
+	@ApiModelProperty(required = true, value = "the text")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getText() {
 		return text;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setText(final String text) {
 		this.text = text;
 	}
 
+	@ApiModelProperty(required = true, value = "true for active question")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final boolean isActive() {
 		return active;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setActive(final boolean active) {
 		this.active = active;
 	}
 
+	@ApiModelProperty(required = true, value = "deprecated - previously used to limitate the audience")
 	public final String getReleasedFor() {
 		return releasedFor;
 	}
@@ -127,14 +178,18 @@ public class Question {
 		this.releasedFor = releasedFor;
 	}
 
-	public final List<PossibleAnswer> getPossibleAnswers() {
-		return possibleAnswers;
+	@ApiModelProperty(required = true, value = "list of possible answers")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final List<AnswerOption> getPossibleAnswers() {
+		return possibleAnswers != null ? possibleAnswers : new ArrayList<>();
 	}
 
-	public final void setPossibleAnswers(final List<PossibleAnswer> possibleAnswers) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final void setPossibleAnswers(final List<AnswerOption> possibleAnswers) {
 		this.possibleAnswers = possibleAnswers;
 	}
 
+	@ApiModelProperty(required = true, value = "if true, no answer is marked correct")
 	public final boolean isNoCorrect() {
 		return noCorrect;
 	}
@@ -143,14 +198,18 @@ public class Question {
 		this.noCorrect = noCorrect;
 	}
 
+	@ApiModelProperty(required = true, value = "couchDB ID of the session, the question is assigned to")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final String getSessionId() {
 		return sessionId;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setSessionId(final String sessionId) {
 		this.sessionId = sessionId;
 	}
 
+	@ApiModelProperty(required = true, value = "couchDB ID of the session, the question is assigned to")
 	public final String getSession() {
 		return sessionId;
 	}
@@ -159,22 +218,28 @@ public class Question {
 		sessionId = session;
 	}
 
+	@ApiModelProperty(required = true, value = "the room keyword, the question is assigned to")
 	public final String getSessionKeyword() {
 		return sessionKeyword;
 	}
 
+	//@JsonView(View.Public.class)
 	public final void setSessionKeyword(final String keyword) {
 		sessionKeyword = keyword;
 	}
 
+	@ApiModelProperty(required = true, value = "creation date timestamp")
+	@JsonView(View.Persistence.class)
 	public final long getTimestamp() {
 		return timestamp;
 	}
 
+	@JsonView(View.Persistence.class)
 	public final void setTimestamp(final long timestamp) {
 		this.timestamp = timestamp;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display number")
 	public final int getNumber() {
 		return number;
 	}
@@ -183,265 +248,469 @@ public class Question {
 		this.number = number;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display duration")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final int getDuration() {
 		return duration;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setDuration(final int duration) {
 		this.duration = duration;
 	}
 
+	@ApiModelProperty(required = true, value = "true for image question")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final boolean isImageQuestion() {
+		return imageQuestion;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setImageQuestion(final boolean imageQuestion) {
+		this.imageQuestion = imageQuestion;
+	}
+
+	@ApiModelProperty(required = true, value = "the peer instruction round no.")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getPiRound() {
 		return piRound;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPiRound(final int piRound) {
 		this.piRound = piRound;
 	}
 
+	@ApiModelProperty(required = true, value = "the peer instruction round end timestamp")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public long getPiRoundEndTime() {
 		return piRoundEndTime;
 	}
 
-	public void setPiRoundEndTime(long piRoundEndTime) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setPiRoundEndTime(final long piRoundEndTime) {
 		this.piRoundEndTime = piRoundEndTime;
 	}
 
+	@ApiModelProperty(required = true, value = "the peer instruction round start timestamp")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public long getPiRoundStartTime() {
 		return piRoundStartTime;
 	}
 
-	public void setPiRoundStartTime(long piRoundStartTime) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setPiRoundStartTime(final long piRoundStartTime) {
 		this.piRoundStartTime = piRoundStartTime;
 	}
 
+	@ApiModelProperty(required = true, value = "true for active peer instruction round")
 	public boolean isPiRoundActive() {
 		return piRoundActive;
 	}
 
-	public void setPiRoundActive(boolean piRoundActive) {
+	public void setPiRoundActive(final boolean piRoundActive) {
 		this.piRoundActive = piRoundActive;
 	}
 
+	@ApiModelProperty(required = true, value = "true for finished peer instruction round")
+	public boolean isPiRoundFinished() {
+		return piRoundFinished;
+	}
+
+	public void setPiRoundFinished(final boolean piRoundFinished) {
+		this.piRoundFinished = piRoundFinished;
+	}
+
+	@ApiModelProperty(required = true, value = "used to display showStatistic")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isShowStatistic() {
 		return showStatistic;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setShowStatistic(final boolean showStatistic) {
 		this.showStatistic = showStatistic;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display cvIsColored")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean getCvIsColored() {
 		return cvIsColored;
 	}
 
-	public void setCvIsColored(boolean cvIsColored) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setCvIsColored(final boolean cvIsColored) {
 		this.cvIsColored = cvIsColored;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display showAnswer")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isShowAnswer() {
 		return showAnswer;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setShowAnswer(final boolean showAnswer) {
 		this.showAnswer = showAnswer;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display abstention")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isAbstention() {
 		return abstention;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setAbstention(final boolean abstention) {
 		this.abstention = abstention;
 	}
 
-	public final String get_id() {
-		return _id;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isIgnoreCaseSensitive() {
+		return ignoreCaseSensitive;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setIgnoreCaseSensitive(final boolean ignoreCaseSensitive) {
+		this.ignoreCaseSensitive = ignoreCaseSensitive;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isIgnoreWhitespaces() {
+		return ignoreWhitespaces;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setIgnoreWhitespaces(final boolean ignoreWhitespaces) {
+		this.ignoreWhitespaces = ignoreWhitespaces;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isIgnorePunctuation() {
+		return ignorePunctuation;
 	}
 
-	public final void set_id(final String _id) {
-		this._id = _id;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setIgnorePunctuation(final boolean ignorePunctuation) {
+		this.ignorePunctuation = ignorePunctuation;
 	}
 
-	public final String get_rev() {
-		return _rev;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isFixedAnswer() {
+		return this.fixedAnswer;
 	}
 
-	public final void set_rev(final String _rev) {
-		this._rev = _rev;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFixedAnswer(final boolean fixedAnswer) {
+		this.fixedAnswer = fixedAnswer;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isStrictMode() {
+		return this.strictMode;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setStrictMode(final boolean strictMode) {
+		this.strictMode = strictMode;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final int getRating() {
+		return this.rating;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final void setRating(final int rating) {
+		this.rating = rating;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final String getCorrectAnswer() {
+		return correctAnswer;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public final void setCorrectAnswer(final String correctAnswer) {
+		this.correctAnswer = correctAnswer;
+	}
+
+	@ApiModelProperty(required = true, value = "the image")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getImage() {
 		return image;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setImage(final String image) {
 		this.image = image;
 	}
 
+	@ApiModelProperty(required = true, value = "the fcImage")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getFcImage() {
 		return fcImage;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setFcImage(final String fcImage) {
 		this.fcImage = fcImage;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid size")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getGridSize() {
 		return gridSize;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridSize(final int gridSize) {
 		this.gridSize = gridSize;
 	}
 
+	@ApiModelProperty(required = true, value = "the image X offset")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getOffsetX() {
 		return offsetX;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setOffsetX(final int offsetX) {
 		this.offsetX = offsetX;
 	}
 
+	@ApiModelProperty(required = true, value = "the image Y offset")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getOffsetY() {
 		return offsetY;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setOffsetY(final int offsetY) {
 		this.offsetY = offsetY;
 	}
 
+	@ApiModelProperty(required = true, value = "the image zoom level")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getZoomLvl() {
 		return zoomLvl;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setZoomLvl(final int zoomLvl) {
 		this.zoomLvl = zoomLvl;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid X offset")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getGridOffsetX() {
 		return gridOffsetX;
 	}
 
-	public void setGridOffsetX(int gridOffsetX) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridOffsetX(final int gridOffsetX) {
 		this.gridOffsetX = gridOffsetX;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid Y offset")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getGridOffsetY() {
 		return gridOffsetY;
 	}
 
-	public void setGridOffsetY(int gridOffsetY) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridOffsetY(final int gridOffsetY) {
 		this.gridOffsetY = gridOffsetY;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid zoom lvl")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getGridZoomLvl() {
 		return gridZoomLvl;
 	}
 
-	public void setGridZoomLvl(int gridZoomLvl) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridZoomLvl(final int gridZoomLvl) {
 		this.gridZoomLvl = gridZoomLvl;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid X size")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getGridSizeX() {
 		return gridSizeX;
 	}
 
-	public void setGridSizeX(int gridSizeX) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridSizeX(final int gridSizeX) {
 		this.gridSizeX = gridSizeX;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid Y size")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getGridSizeY() {
 		return gridSizeY;
 	}
 
-	public void setGridSizeY(int gridSizeY) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridSizeY(final int gridSizeY) {
 		this.gridSizeY = gridSizeY;
 	}
 
+	@ApiModelProperty(required = true, value = "true for hidden grid")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean getGridIsHidden() {
 		return gridIsHidden;
 	}
 
-	public void setGridIsHidden(boolean gridIsHidden) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridIsHidden(final boolean gridIsHidden) {
 		this.gridIsHidden = gridIsHidden;
 	}
 
+	@ApiModelProperty(required = true, value = "the image rotation")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getImgRotation() {
 		return imgRotation;
 	}
 
-	public void setImgRotation(int imgRotation) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setImgRotation(final int imgRotation) {
 		this.imgRotation = imgRotation;
 	}
 
+	@ApiModelProperty(required = true, value = "the toggled left fields")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean getToggleFieldsLeft() {
 		return toggleFieldsLeft;
 	}
 
-	public void setToggleFieldsLeft(boolean toggleFieldsLeft) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setToggleFieldsLeft(final boolean toggleFieldsLeft) {
 		this.toggleFieldsLeft = toggleFieldsLeft;
 	}
 
+	@ApiModelProperty(required = true, value = "the number of clickable fields")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getNumClickableFields() {
 		return numClickableFields;
 	}
 
-	public void setNumClickableFields(int numClickableFields) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setNumClickableFields(final int numClickableFields) {
 		this.numClickableFields = numClickableFields;
 	}
 
+	@ApiModelProperty(required = true, value = "the threshold of correct answers")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getThresholdCorrectAnswers() {
 		return thresholdCorrectAnswers;
 	}
 
-	public void setThresholdCorrectAnswers(int thresholdCorrectAnswers) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setThresholdCorrectAnswers(final int thresholdCorrectAnswers) {
 		this.thresholdCorrectAnswers = thresholdCorrectAnswers;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid line color")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getGridLineColor() {
 		return gridLineColor;
 	}
 
-	public void setGridLineColor(String gridLineColor) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridLineColor(final String gridLineColor) {
 		this.gridLineColor = gridLineColor;
 	}
 
+	@ApiModelProperty(required = true, value = "the number of dots")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getNumberOfDots() {
 		return numberOfDots;
 	}
 
-	public void setNumberOfDots(int numberOfDots) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setNumberOfDots(final int numberOfDots) {
 		this.numberOfDots = numberOfDots;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid type")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getGridType() {
 		return gridType;
 	}
 
-	public void setGridType(String gridType) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridType(final String gridType) {
 		this.gridType = gridType;
 	}
 
-	public void setScaleFactor(String scaleFactor) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setScaleFactor(final String scaleFactor) {
 		this.scaleFactor = scaleFactor;
 	}
 
+	@ApiModelProperty(required = true, value = "the image scale factor")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getScaleFactor() {
 		return this.scaleFactor;
 	}
 
-	public void setGridScaleFactor(String scaleFactor) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setGridScaleFactor(final String scaleFactor) {
 		this.gridScaleFactor = scaleFactor;
 	}
 
+	@ApiModelProperty(required = true, value = "the grid scale factor")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getGridScaleFactor() {
 		return this.gridScaleFactor;
 	}
 
+	@ApiModelProperty(required = true, value = "true for a question that can be answered via text")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isTextAnswerEnabled() {
+		return this.textAnswerEnabled;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setTextAnswerEnabled(final boolean textAnswerEnabled) {
+		this.textAnswerEnabled = textAnswerEnabled;
+	}
+
+	@ApiModelProperty(required = true, value = "true for disabled voting")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isVotingDisabled() {
+		return votingDisabled;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setVotingDisabled(final boolean votingDisabled) {
+		this.votingDisabled = votingDisabled;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getHint() {
+		return hint;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setHint(final String hint) {
+		this.hint = hint;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getSolution() {
+		return solution;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setSolution(final String solution) {
+		this.solution = solution;
+	}
+
 	@Override
 	public final String toString() {
-		return "Question type '" + type + "': " + subject + ";\n" + text + possibleAnswers;
+		return "Content type '" + questionType + "': " + subject + ";\n" + text + possibleAnswers;
 	}
 
 	@Override
@@ -449,52 +718,141 @@ public class Question {
 		// auto generated!
 		final int prime = 31;
 		int result = 1;
-		result = prime * result + ((_id == null) ? 0 : _id.hashCode());
-		result = prime * result + ((_rev == null) ? 0 : _rev.hashCode());
+		result = prime * result + ((id == null) ? 0 : id.hashCode());
 		return result;
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(final Object obj) {
 		// auto generated!
-		if (this == obj) return true;
-		if (obj == null) return false;
-		if (getClass() != obj.getClass()) {
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null) {
 			return false;
 		}
-		Question other = (Question) obj;
-		if (_id == null) {
-			if (other._id != null) {
-				return false;
-			}
-		} else if (!_id.equals(other._id)) {
+		if (getClass() != obj.getClass()) {
 			return false;
 		}
-		if (_rev == null) {
-			if (other._rev != null) {
+		final Content other = (Content) obj;
+		if (id == null) {
+			if (other.id != null) {
 				return false;
 			}
-		} else if (!_rev.equals(other._rev)) {
+		} else if (!id.equals(other.id)) {
 			return false;
 		}
 		return true;
 	}
 
-	public int calculateValue(Answer answer) {
+	public int calculateValue(final Answer answer) {
 		if (answer.isAbstention()) {
 			return 0;
-		} else if (this.questionType.equals("mc")) {
+		} else if ("mc".equals(this.questionType)) {
 			return calculateMultipleChoiceValue(answer);
-		} else if (this.questionType.equals("grid")) {
+		} else if ("grid".equals(this.questionType)) {
 			return calculateGridValue(answer);
 		} else {
 			return calculateRegularValue(answer);
 		}
 	}
 
-	private int calculateRegularValue(Answer answer) {
-		String answerText = answer.getAnswerText();
-		for (PossibleAnswer p : this.possibleAnswers) {
+	public String checkCaseSensitive(final String answerText) {
+		if (this.isIgnoreCaseSensitive()) {
+			this.setCorrectAnswer(this.getCorrectAnswer().toLowerCase());
+			return answerText.toLowerCase();
+		}
+		return answerText;
+	}
+
+	public String checkWhitespaces(final String answerText) {
+		if (this.isIgnoreWhitespaces()) {
+			this.setCorrectAnswer(this.getCorrectAnswer().replaceAll("[\\s]", ""));
+			return answerText.replaceAll("[\\s]", "");
+		}
+		return answerText;
+	}
+
+	public String checkPunctuation(final String answerText) {
+		if (this.isIgnorePunctuation()) {
+			this.setCorrectAnswer(this.getCorrectAnswer().replaceAll("\\p{Punct}", ""));
+			return answerText.replaceAll("\\p{Punct}", "");
+		}
+		return answerText;
+	}
+
+	public void checkTextStrictOptions(final Answer answer) {
+		answer.setAnswerTextRaw(this.checkCaseSensitive(answer.getAnswerTextRaw()));
+		answer.setAnswerTextRaw(this.checkPunctuation(answer.getAnswerTextRaw()));
+		answer.setAnswerTextRaw(this.checkWhitespaces(answer.getAnswerTextRaw()));
+	}
+
+	public int evaluateCorrectAnswerFixedText(final String answerTextRaw) {
+		if (answerTextRaw != null) {
+			if (answerTextRaw.equals(this.getCorrectAnswer())) {
+				return this.getRating();
+			}
+		}
+		return 0;
+	}
+
+	public boolean isSuccessfulFreeTextAnswer(final String answerTextRaw) {
+		return answerTextRaw != null && answerTextRaw.equals(this.getCorrectAnswer());
+	}
+
+	public void updateRoundStartVariables(final Date start, final Date end) {
+		if (this.getPiRound() == 1 && this.isPiRoundFinished()) {
+			this.setPiRound(2);
+		}
+
+		this.setActive(true);
+		this.setShowAnswer(false);
+		this.setPiRoundActive(true);
+		this.setShowStatistic(false);
+		this.setVotingDisabled(false);
+		this.setPiRoundFinished(false);
+		this.setPiRoundStartTime(start.getTime());
+		this.setPiRoundEndTime(end.getTime());
+	}
+
+	public void updateRoundManagementState() {
+		final long time = new Date().getTime();
+
+		if (time > this.getPiRoundEndTime() && this.isPiRoundActive()) {
+			this.setPiRoundEndTime(0);
+			this.setPiRoundStartTime(0);
+			this.setPiRoundActive(false);
+			this.setPiRoundFinished(true);
+		}
+	}
+
+	public void resetRoundManagementState() {
+		this.setPiRoundEndTime(0);
+		this.setPiRoundStartTime(0);
+		this.setVotingDisabled(true);
+		this.setPiRoundActive(false);
+		this.setPiRoundFinished(false);
+		this.setShowStatistic(false);
+		this.setShowAnswer(false);
+	}
+
+	public void resetQuestionState() {
+		this.setPiRoundEndTime(0);
+		this.setPiRoundStartTime(0);
+		this.setPiRoundActive(false);
+		this.setPiRoundFinished(false);
+		this.setVotingDisabled(false);
+
+		if ("freetext".equals(this.getQuestionType())) {
+			this.setPiRound(0);
+		} else {
+			this.setPiRound(1);
+		}
+	}
+
+	private int calculateRegularValue(final Answer answer) {
+		final String answerText = answer.getAnswerText();
+		for (final AnswerOption p : this.possibleAnswers) {
 			if (answerText.equals(p.getText())) {
 				return p.getValue();
 			}
@@ -502,12 +860,12 @@ public class Question {
 		return 0;
 	}
 
-	private int calculateGridValue(Answer answer) {
+	private int calculateGridValue(final Answer answer) {
 		int value = 0;
-		String[] answers = answer.getAnswerText().split(",");
-		for (int i = 0; i < answers.length; i++) {
-			for (PossibleAnswer p : this.possibleAnswers) {
-				if (answers[i].equals(p.getText())) {
+		final String[] answers = answer.getAnswerText().split(",");
+		for (final String a : answers) {
+			for (final AnswerOption p : this.possibleAnswers) {
+				if (a.equals(p.getText())) {
 					value += p.getValue();
 				}
 			}
@@ -515,12 +873,12 @@ public class Question {
 		return value;
 	}
 
-	private int calculateMultipleChoiceValue(Answer answer) {
+	private int calculateMultipleChoiceValue(final Answer answer) {
 		int value = 0;
-		String[] answers = answer.getAnswerText().split(",");
+		final String[] answers = answer.getAnswerText().split(",");
 		for (int i = 0; i < this.possibleAnswers.size() && i < answers.length; i++) {
-			if (answers[i].equals("1")) {
-				PossibleAnswer p = this.possibleAnswers.get(i);
+			if ("1".equals(answers[i])) {
+				final AnswerOption p = this.possibleAnswers.get(i);
 				value += p.getValue();
 			}
 		}

src/main/java/de/thm/arsnova/entities/DbUser.java → src/main/java/de/thm/arsnova/model/migration/v2/DbUser.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,9 +15,17 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
-public class DbUser {
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * A user account for ARSnova's own registration and login process.
+ */
+public class DbUser implements Entity {
 	private String id;
 	private String rev;
 	private String username;
@@ -28,90 +36,93 @@ public class DbUser {
 	private long creation;
 	private long lastLogin;
 
+	@JsonView(View.Persistence.class)
 	public String getId() {
 		return id;
 	}
 
-	public void setId(String id) {
-		this.id = id;
-	}
-
-	/* CouchDB deserialization */
-	public void set_id(String id) {
+	@JsonView(View.Persistence.class)
+	public void setId(final String id) {
 		this.id = id;
 	}
 
-	public String getRev() {
+	@JsonView(View.Persistence.class)
+	public String getRevision() {
 		return rev;
 	}
 
-	public void setRev(String rev) {
-		this.rev = rev;
-	}
-
-	/* CouchDB deserialization */
-	public void set_rev(String rev) {
+	@JsonView(View.Persistence.class)
+	public void setRevision(final String rev) {
 		this.rev = rev;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getUsername() {
 		return username;
 	}
 
-	public void setUsername(String username) {
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setUsername(final String username) {
 		this.username = username;
 	}
 
+	@JsonView(View.Persistence.class)
 	public String getPassword() {
 		return password;
 	}
 
-	public void setPassword(String password) {
+	@JsonView(View.Persistence.class)
+	public void setPassword(final String password) {
 		this.password = password;
 	}
 
+	@JsonView(View.Persistence.class)
 	public String getActivationKey() {
 		return activationKey;
 	}
 
-	public void setActivationKey(String activationKey) {
+	@JsonView(View.Persistence.class)
+	public void setActivationKey(final String activationKey) {
 		this.activationKey = activationKey;
 	}
 
+	@JsonView(View.Persistence.class)
 	public String getPasswordResetKey() {
 		return passwordResetKey;
 	}
 
-	public void setPasswordResetKey(String passwordResetKey) {
+	@JsonView(View.Persistence.class)
+	public void setPasswordResetKey(final String passwordResetKey) {
 		this.passwordResetKey = passwordResetKey;
 	}
 
+	@JsonView(View.Persistence.class)
 	public long getPasswordResetTime() {
 		return passwordResetTime;
 	}
 
-	public void setPasswordResetTime(long passwordResetTime) {
+	@JsonView(View.Persistence.class)
+	public void setPasswordResetTime(final long passwordResetTime) {
 		this.passwordResetTime = passwordResetTime;
 	}
 
+	@JsonView(View.Persistence.class)
 	public long getCreation() {
 		return creation;
 	}
 
-	public void setCreation(long creation) {
+	@JsonView(View.Persistence.class)
+	public void setCreation(final long creation) {
 		this.creation = creation;
 	}
 
+	@JsonView(View.Persistence.class)
 	public long getLastLogin() {
 		return lastLogin;
 	}
 
-	public void setLastLogin(long lastLogin) {
+	@JsonView(View.Persistence.class)
+	public void setLastLogin(final long lastLogin) {
 		this.lastLogin = lastLogin;
 	}
-
-	/* CouchDB deserialization */
-	public void setType(String type) {
-		/* no op */
-	}
 }

src/main/java/de/thm/arsnova/events/DeleteQuestionEvent.java → src/main/java/de/thm/arsnova/model/migration/v2/Entity.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2017 The ARSnova Team
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,21 +15,24 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Session;
+package de.thm.arsnova.model.migration.v2;
 
-public class DeleteQuestionEvent extends SessionEvent {
+import com.fasterxml.jackson.annotation.JsonView;
 
-	private static final long serialVersionUID = 1L;
+import de.thm.arsnova.model.serialization.View;
 
-	public DeleteQuestionEvent(Object source, Session session) {
-		super(source, session);
-	}
+public interface Entity {
+	String getId();
 
-	@Override
-	public void accept(NovaEventVisitor visitor) {
-		visitor.visit(this);
-	}
+	void setId(String id);
+
+	String getRevision();
 
+	void setRevision(String rev);
+
+	@JsonView(View.Persistence.class)
+	default Class<? extends Entity> getType() {
+		return getClass();
+	}
 }

src/main/java/de/thm/arsnova/model/migration/v2/LogEntry.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonView;
+import java.util.Map;
+
+import de.thm.arsnova.model.serialization.View;
+
+public class LogEntry implements Entity {
+	public enum LogLevel {
+		TRACE,
+		DEBUG,
+		INFO,
+		WARN,
+		ERROR,
+		FATAL
+	}
+
+	private String id;
+	private String rev;
+	private long timestamp = System.currentTimeMillis();
+	private String event;
+	private int level;
+	private Map<String, Object> payload;
+
+	public LogEntry(@JsonProperty final String event, @JsonProperty final int level,
+			@JsonProperty final Map<String, Object> payload) {
+		this.event = event;
+		this.level = level;
+		this.payload = payload;
+	}
+
+	@JsonView(View.Persistence.class)
+	public String getId() {
+		return id;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@JsonView(View.Persistence.class)
+	public String getRevision() {
+		return rev;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setRevision(final String rev) {
+		this.rev = rev;
+	}
+
+	@JsonView(View.Persistence.class)
+	public long getTimestamp() {
+		return timestamp;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setTimestamp(final long timestamp) {
+		this.timestamp = timestamp;
+	}
+
+	@JsonView(View.Persistence.class)
+	public String getEvent() {
+		return event;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setEvent(final String event) {
+		this.event = event;
+	}
+
+	@JsonView(View.Persistence.class)
+	public int getLevel() {
+		return level;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setLevel(final int level) {
+		this.level = level;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setLevel(final LogLevel level) {
+		this.level = level.ordinal();
+	}
+
+	@JsonView(View.Persistence.class)
+	public Map<String, Object> getPayload() {
+		return payload;
+	}
+
+	@JsonView(View.Persistence.class)
+	public void setPayload(final Map<String, Object> payload) {
+		this.payload = payload;
+	}
+}

src/main/java/de/thm/arsnova/entities/LoggedIn.java → src/main/java/de/thm/arsnova/model/migration/v2/LoggedIn.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,117 +15,125 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
 import java.util.ArrayList;
 import java.util.List;
 
-public class LoggedIn {
+import de.thm.arsnova.model.serialization.View;
 
-	private String _id;
-	private String _rev;
-	private String type;
+/**
+ * Once a user joins a session, this class is used to identify a returning user.
+ */
+@ApiModel(value = "LoggedIn", description = "Logged In entity - Contains the Room History (Visited Sessions)")
+public class LoggedIn implements Entity {
+	private String id;
+	private String rev;
 	private String user;
 	private String sessionId;
 	private long timestamp;
-	private List<VisitedSession> visitedSessions = new ArrayList<VisitedSession>();
-	private List<String> _conflicts;
+	private List<VisitedRoom> visitedSessions = new ArrayList<>();
+	private boolean anonymized;
 
 	public LoggedIn() {
-		this.type = "logged_in";
 		this.updateTimestamp();
 	}
 
-	public void addVisitedSession(Session s) {
+	public void addVisitedSession(final Room s) {
 		if (!isAlreadyVisited(s)) {
-			this.visitedSessions.add(new VisitedSession(s));
+			this.visitedSessions.add(new VisitedRoom(s));
 		}
 	}
 
-	private boolean isAlreadyVisited(Session s) {
-		for (VisitedSession vs : this.visitedSessions) {
-			if (vs.get_id().equals(s.get_id())) {
+	private boolean isAlreadyVisited(final Room s) {
+		for (final VisitedRoom vs : this.visitedSessions) {
+			if (vs.getId().equals(s.getId())) {
 				return true;
 			}
 		}
 		return false;
 	}
 
-	public void updateTimestamp() {
-		this.timestamp = System.currentTimeMillis();
-	}
-
-	public String get_id() {
-		return _id;
+	@JsonView(View.Persistence.class)
+	public String getId() {
+		return id;
 	}
 
-	public void set_id(String _id) {
-		this._id = _id;
+	@JsonView(View.Persistence.class)
+	public void setId(final String id) {
+		this.id = id;
 	}
 
-	public String get_rev() {
-		return _rev;
+	@JsonView(View.Persistence.class)
+	public String getRevision() {
+		return rev;
 	}
 
-	public void set_rev(String _rev) {
-		this._rev = _rev;
+	@JsonView(View.Persistence.class)
+	public void setRevision(final String rev) {
+		this.rev = rev;
 	}
 
-	public String getType() {
-		return type;
-	}
-
-	public void setType(String type) {
-		this.type = type;
+	public void updateTimestamp() {
+		this.timestamp = System.currentTimeMillis();
 	}
 
+	@JsonView(View.Persistence.class)
 	public String getUser() {
 		return user;
 	}
 
-	public void setUser(String user) {
+	@JsonView(View.Persistence.class)
+	public void setUser(final String user) {
 		this.user = user;
 	}
 
+	@JsonView(View.Persistence.class)
 	public String getSessionId() {
 		return sessionId;
 	}
 
-	public void setSessionId(String sessionId) {
+	@JsonView(View.Persistence.class)
+	public void setSessionId(final String sessionId) {
 		this.sessionId = sessionId;
 	}
 
+	@JsonView(View.Persistence.class)
 	public long getTimestamp() {
 		return timestamp;
 	}
 
-	public void setTimestamp(long timestamp) {
+	@JsonView(View.Persistence.class)
+	public void setTimestamp(final long timestamp) {
 		this.timestamp = timestamp;
 	}
 
-	public List<VisitedSession> getVisitedSessions() {
+	@JsonView(View.Persistence.class)
+	public List<VisitedRoom> getVisitedSessions() {
 		return visitedSessions;
 	}
 
-	public void setVisitedSessions(List<VisitedSession> visitedSessions) {
+	@JsonView(View.Persistence.class)
+	public void setVisitedSessions(final List<VisitedRoom> visitedSessions) {
 		this.visitedSessions = visitedSessions;
 	}
 
-	public List<String> get_conflicts() {
-		return _conflicts;
-	}
-
-	public void set_conflicts(List<String> _conflicts) {
-		this._conflicts = _conflicts;
+	@JsonView(View.Persistence.class)
+	public boolean isAnonymized() {
+		return anonymized;
 	}
 
-	public boolean hasConflicts() {
-		return !(_conflicts == null || _conflicts.isEmpty());
+	@JsonView(View.Persistence.class)
+	public void setAnonymized(final boolean anonymized) {
+		this.anonymized = anonymized;
 	}
 
 	@Override
 	public String toString() {
-		return "LoggedIn [_id=" + _id + ", _rev=" + _rev + ", type=" + type
+		return "LoggedIn [id=" + id + ", rev=" + rev + ", type=" + getType()
 				+ ", user=" + user + ", sessionId=" + sessionId
 				+ ", timestamp=" + timestamp + ", visitedSessions="
 				+ visitedSessions + "]";

src/main/java/de/thm/arsnova/model/migration/v2/Motd.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+import java.util.Date;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * Represents a Message of the Day.
+ */
+@ApiModel(value = "Motd", description = "Message of the Day entity")
+public class Motd implements Entity {
+
+	private String motdkey; //ID
+	private Date startdate;
+	private Date enddate;
+	private String title;
+	private String text;
+	private String audience;
+	private String sessionId;
+	private String sessionkey;
+	private String id;
+	private String rev;
+
+	@ApiModelProperty(required = true, value = "the identification string")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getMotdkey() {
+		return motdkey;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setMotdkey(final String key) {
+		motdkey = key;
+	}
+
+	@ApiModelProperty(required = true, value = "startdate for showing this message (timestamp format)")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public Date getStartdate() {
+		return startdate;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setStartdate(final Date timestamp) {
+		startdate = timestamp;
+	}
+
+	@ApiModelProperty(required = true, value = "enddate for showing this message (timestamp format)")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public Date getEnddate() {
+		return enddate;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setEnddate(final Date timestamp) {
+		enddate = timestamp;
+	}
+
+	@ApiModelProperty(required = true, value = "tite of the message")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getTitle() {
+		return title;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setTitle(final String title) {
+		this.title = title;
+	}
+
+	@ApiModelProperty(required = true, value = "text of the message")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getText() {
+		return text;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setText(final String ttext) {
+		text = ttext;
+	}
+
+	@ApiModelProperty(required = true, value = "defines the target audience for this motd (one of the following: "
+			+ "'student', 'tutor', 'loggedIn', 'all')")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getAudience() {
+		return audience;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setAudience(final String a) {
+		audience = a;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getSessionId() {
+		return sessionId;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setSessionId(final String sessionId) {
+		this.sessionId = sessionId;
+	}
+
+	@ApiModelProperty(required = true,
+			value = "when audience equals session, the sessionkey referes to the session the messages belong to")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getSessionkey() {
+		return sessionkey;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setSessionkey(final String a) {
+		sessionkey = a;
+	}
+
+	@ApiModelProperty(required = true, value = "the couchDB ID")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getId() {
+		return id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRevision(final String rev) {
+		this.rev = rev;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getRevision() {
+		return rev;
+	}
+
+	@Override
+	public int hashCode() {
+		// See http://stackoverflow.com/a/113600
+		final int prim = 37;
+
+		final int result = 42;
+		return prim * result + this.motdkey.hashCode();
+	}
+
+	@Override
+	public boolean equals(final Object obj) {
+		if (obj == null || !obj.getClass().equals(this.getClass())) {
+			return false;
+		}
+		final Motd other = (Motd) obj;
+		return this.getMotdkey().equals(other.getMotdkey());
+	}
+}

src/main/java/de/thm/arsnova/model/migration/v2/MotdList.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * Contains a list of MotD IDs a user has acknowledged.
+ */
+@ApiModel(value = "MotdList", description = "Motd List entity - Contains IDs of MotDs a user has acknowledged")
+public class MotdList implements Entity {
+	private String id;
+	private String rev;
+	private String motdkeys;
+	private String username;
+
+	@ApiModelProperty(required = true, value = "the couchDB ID")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getId() {
+		return id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRevision(final String rev) {
+		this.rev = rev;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getRevision() {
+		return rev;
+	}
+
+	@ApiModelProperty(required = true, value = "the motdkeylist")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getMotdkeys() {
+		return motdkeys;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setMotdkeys(final String motds) {
+		motdkeys = motds;
+	}
+
+	@ApiModelProperty(required = true, value = "the username")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getUsername() {
+		return username;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setUsername(final String u) {
+		username = u;
+	}
+}

src/main/java/de/thm/arsnova/entities/Session.java → src/main/java/de/thm/arsnova/model/migration/v2/Room.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,18 +15,24 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
-import java.io.Serializable;
-import java.util.List;
+package de.thm.arsnova.model.migration.v2;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
 
-public class Session implements Serializable {
+import de.thm.arsnova.model.ScoreOptions;
+import de.thm.arsnova.model.serialization.View;
 
-	private static final long serialVersionUID = 1L;
-
-	private String type;
+/**
+ * Represents a Room (Session).
+ */
+@ApiModel(value = "Room", description = "Room (Session) entity")
+public class Room implements Entity {
+	private String id;
+	private String rev;
 	private String name;
 	private String shortName;
 	private String keyword;
@@ -35,9 +41,9 @@ public class Session implements Serializable {
 	private long lastOwnerActivity;
 	private String courseType;
 	private String courseId;
-	private List<String> _conflicts;
 	private long creationTime;
-	private String learningProgressType = "questions";
+	private ScoreOptions learningProgressOptions = new ScoreOptions();
+	private RoomFeature features = new RoomFeature();
 
 	private String ppAuthorName;
 	private String ppAuthorMail;
@@ -49,141 +55,117 @@ public class Session implements Serializable {
 	private String ppFaculty;
 	private String ppLevel;
 	private String sessionType;
+	private boolean feedbackLock;
+	private boolean flipFlashcards;
 
-	private String _id;
-	private String _rev;
-
-	/**
-	 * Returns a copy of the given session without any information that identifies a person.
-	 * @param original The session to create a anonymized copy of
-	 * @return
-	 */
-	public static Session anonymizedCopy(final Session original) {
-		final Session copy = new Session();
-		copy.type = original.type;
-		copy.name = original.name;
-		copy.shortName = original.shortName;
-		copy.keyword = original.keyword;
-		copy.creator = ""; // anonymous
-		copy.active = original.active;
-		copy.lastOwnerActivity = original.lastOwnerActivity;
-		copy.courseType = original.courseType;
-		copy.courseId = original.courseId;
-		copy.creationTime = original.creationTime;
-		copy.learningProgressType = original.learningProgressType;
-		// public pool
-		copy.ppAuthorName = original.ppAuthorName;
-		copy.ppAuthorMail = original.ppAuthorMail;
-		copy.ppUniversity = original.ppUniversity;
-		copy.ppLogo = original.ppLogo;
-		copy.ppSubject = original.ppSubject;
-		copy.ppLicense = original.ppLicense;
-		copy.ppDescription = original.ppDescription;
-		copy.ppFaculty = original.ppFaculty;
-		copy.ppLevel = original.ppLevel;
-		copy.sessionType = original.sessionType;
-
-		copy._id = original._id;
-		copy._rev = original._rev;
-		return copy;
-	}
-
-	public String getType() {
-		return type;
-	}
-
-	public void setType(final String type) {
-		this.type = type;
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getId() {
+		return id;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getRevision() {
+		return rev;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setRevision(final String rev) {
+		this.rev = rev;
+	}
+
+	@ApiModelProperty(required = true, value = "the name")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getName() {
 		return name;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setName(final String name) {
 		this.name = name;
 	}
 
+	@ApiModelProperty(required = true, value = "the short name")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getShortName() {
 		return shortName;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setShortName(final String shortName) {
 		this.shortName = shortName;
 	}
 
+	@ApiModelProperty(required = true, value = "the keyword")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getKeyword() {
 		return keyword;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setKeyword(final String keyword) {
 		this.keyword = keyword;
 	}
 
+	@ApiModelProperty(required = true, value = "the session creator")
+	@JsonView(View.Persistence.class)
 	public String getCreator() {
 		return creator;
 	}
 
+	@JsonView(View.Persistence.class)
 	public void setCreator(final String creator) {
 		this.creator = creator;
 	}
 
+	@ApiModelProperty(required = true, value = "true for active session")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isActive() {
 		return active;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setActive(final boolean active) {
 		this.active = active;
 	}
 
+	@ApiModelProperty(required = true, value = "timestamp from the last activity of the owner")
+	@JsonView(View.Persistence.class)
 	public long getLastOwnerActivity() {
 		return lastOwnerActivity;
 	}
 
+	@JsonView(View.Persistence.class)
 	public void setLastOwnerActivity(final long lastOwnerActivity) {
 		this.lastOwnerActivity = lastOwnerActivity;
 	}
 
-	public void set_id(final String id) {
-		_id = id;
-	}
-
-	public String get_id() {
-		return _id;
-	}
-
-	public void set_rev(final String rev) {
-		_rev = rev;
-	}
-
-	public String get_rev() {
-		return _rev;
-	}
-
-	public void set_conflicts(final List<String> conflicts) {
-		_conflicts = conflicts;
-	}
-
-	public List<String> get_conflicts() {
-		return _conflicts;
-	}
-
-	public boolean isCreator(final User user) {
+	public boolean isCreator(final ClientAuthentication user) {
 		return user.getUsername().equals(creator);
 	}
 
+	@ApiModelProperty(required = true, value = "the source the course comes from (example: moodle)")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getCourseType() {
 		return courseType;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setCourseType(final String courseType) {
 		this.courseType = courseType;
 	}
 
+	@ApiModelProperty(required = true, value = "the course ID")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getCourseId() {
 		return courseId;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setCourseId(final String courseId) {
 		this.courseId = courseId;
 	}
@@ -193,105 +175,183 @@ public class Session implements Serializable {
 		return getCourseId() != null && !getCourseId().isEmpty();
 	}
 
+	@ApiModelProperty(required = true, value = "creation timestamp")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public long getCreationTime() {
 		return creationTime;
 	}
 
-	public void setCreationTime(long creationTime) {
+	@JsonView(View.Persistence.class)
+	public void setCreationTime(final long creationTime) {
 		this.creationTime = creationTime;
 	}
 
-	public String getLearningProgressType() {
-		return learningProgressType;
+	@ApiModelProperty(required = true, value = "the score options")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public ScoreOptions getLearningProgressOptions() {
+		return learningProgressOptions;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setLearningProgressOptions(final ScoreOptions learningProgressOptions) {
+		this.learningProgressOptions = learningProgressOptions;
 	}
 
-	public void setLearningProgressType(String learningProgressType) {
-		this.learningProgressType = learningProgressType;
+	@ApiModelProperty(required = true,
+			value = "the enabled features (e.g. feedback, interposed, learning Progress, lecture)")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public RoomFeature getFeatures() {
+		return features;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFeatures(final RoomFeature features) {
+		this.features = features;
+	}
+
+	@ApiModelProperty(required = true, value = "the public pool author name")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpAuthorName() {
 		return ppAuthorName;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpAuthorName(final String ppAuthorName) {
 		this.ppAuthorName = ppAuthorName;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool author email")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpAuthorMail() {
 		return ppAuthorMail;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpAuthorMail(final String ppAuthorMail) {
 		this.ppAuthorMail = ppAuthorMail;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool university")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpUniversity() {
 		return ppUniversity;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpUniversity(final String ppUniversity) {
 		this.ppUniversity = ppUniversity;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool logo")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpLogo() {
 		return ppLogo;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpLogo(final String ppLogo) {
 		this.ppLogo = ppLogo;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display subject")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpSubject() {
 		return ppSubject;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpSubject(final String ppSubject) {
 		this.ppSubject = ppSubject;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool license")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpLicense() {
 		return ppLicense;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpLicense(final String ppLicense) {
 		this.ppLicense = ppLicense;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool description")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpDescription() {
 		return ppDescription;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpDescription(final String ppDescription) {
 		this.ppDescription = ppDescription;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool faculty")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpFaculty() {
 		return ppFaculty;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpFaculty(final String ppFaculty) {
 		this.ppFaculty = ppFaculty;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool level")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getPpLevel() {
 		return ppLevel;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPpLevel(final String ppLevel) {
 		this.ppLevel = ppLevel;
 	}
 
+	@ApiModelProperty(required = true, value = "the session type")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getSessionType() {
 		return sessionType;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setSessionType(final String sessionType) {
 		this.sessionType = sessionType;
 	}
 
+	@ApiModelProperty(required = true, value = "the feedback lock status")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean getFeedbackLock() {
+		return feedbackLock;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFeedbackLock(final Boolean lock) {
+		this.feedbackLock = lock;
+	}
+
+	@ApiModelProperty(required = true, value = "the flashcard flip condition")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean getFlipFlashcards() {
+		return flipFlashcards;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFlipFlashcards(final Boolean flip) {
+		this.flipFlashcards = flip;
+	}
+
+	public boolean hasAuthorDetails() {
+		return ppAuthorName != null && !ppAuthorName.isEmpty()
+				|| ppAuthorMail != null && !ppAuthorMail.isEmpty()
+				|| ppUniversity != null && !ppUniversity.isEmpty()
+				|| ppFaculty != null && !ppFaculty.isEmpty()
+				|| ppLogo != null && !ppLogo.isEmpty();
+	}
+
 	@Override
 	public String toString() {
-		return "Session [keyword=" + keyword + ", type=" + type + ", creator=" + creator + "]";
+		return "Room [keyword=" + keyword + ", type=" + getType() + ", creator=" + creator + "]";
 	}
 
 	@Override
@@ -304,11 +364,11 @@ public class Session implements Serializable {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(final Object obj) {
 		if (obj == null || !obj.getClass().equals(this.getClass())) {
 			return false;
 		}
-		Session other = (Session) obj;
+		final Room other = (Room) obj;
 		return this.keyword.equals(other.keyword);
 	}
 

src/main/java/de/thm/arsnova/model/migration/v2/RoomFeature.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+import java.io.Serializable;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * Contains fields that describe which specific Feature is activated for a Room.
+ */
+@ApiModel(value = "RoomFeature",
+		description = "Room (Session) Feature entity - Represents feature/use case settings of a Room")
+public class RoomFeature implements Serializable {
+
+	private boolean custom = false;
+	private boolean clicker = false;
+	private boolean peerGrading = false;
+	private boolean twitterWall = false;
+	private boolean liveFeedback = false;
+	private boolean interposedFeedback = false;
+	private boolean liveClicker = false;
+	private boolean flashcard = false;
+	private boolean total = false;
+
+	private boolean jitt = false;
+	private boolean lecture = false;
+	private boolean feedback = false;
+	private boolean interposed = false;
+	private boolean pi = false;
+	private boolean learningProgress = false;
+	private boolean flashcardFeature = false;
+	private boolean slides = false;
+
+	public RoomFeature(final RoomFeature features) {
+		this();
+		if (features != null) {
+			this.custom = features.custom;
+			this.clicker = features.clicker;
+			this.peerGrading = features.peerGrading;
+			this.twitterWall = features.twitterWall;
+			this.liveFeedback = features.liveFeedback;
+			this.interposedFeedback = features.interposedFeedback;
+			this.liveClicker = features.liveClicker;
+			this.flashcardFeature = features.flashcardFeature;
+			this.flashcard = features.flashcard;
+			this.total = features.total;
+			this.lecture = features.lecture;
+			this.jitt = features.jitt;
+			this.feedback = features.feedback;
+			this.interposed = features.interposed;
+			this.pi = features.pi;
+			this.learningProgress = features.learningProgress;
+			this.slides = features.slides;
+		}
+	}
+
+	public RoomFeature() {
+
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isLecture() {
+		return lecture;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setLecture(final boolean lecture) {
+		this.lecture = lecture;
+	}
+
+	@ApiModelProperty(required = true, value = "jitt")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isJitt() {
+		return jitt;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setJitt(final boolean jitt) {
+		this.jitt = jitt;
+	}
+
+	@ApiModelProperty(required = true, value = "feedback")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isFeedback() {
+		return feedback;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFeedback(final boolean feedback) {
+		this.feedback = feedback;
+	}
+
+	@ApiModelProperty(required = true, value = "interposed")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isInterposed() {
+		return interposed;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setInterposed(final boolean interposed) {
+		this.interposed = interposed;
+	}
+
+	@ApiModelProperty(required = true, value = "peer instruction")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isPi() {
+		return pi;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setPi(final boolean pi) {
+		this.pi = pi;
+	}
+
+	@ApiModelProperty(required = true, value = "score")
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isLearningProgress() {
+		return learningProgress;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setLearningProgress(final boolean learningProgress) {
+		this.learningProgress = learningProgress;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isCustom() {
+		return custom;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setCustom(final boolean custom) {
+		this.custom = custom;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isClicker() {
+		return clicker;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setClicker(final boolean clicker) {
+		this.clicker = clicker;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isPeerGrading() {
+		return peerGrading;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setPeerGrading(final boolean peerGrading) {
+		this.peerGrading = peerGrading;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isFlashcardFeature() {
+		return flashcardFeature;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFlashcardFeature(final boolean flashcardFeature) {
+		this.flashcardFeature = flashcardFeature;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isFlashcard() {
+		return flashcard;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setFlashcard(final boolean flashcard) {
+		this.flashcard = flashcard;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isTotal() {
+		return total;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setTotal(final boolean total) {
+		this.total = total;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isLiveFeedback() {
+		return liveFeedback;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setLiveFeedback(final boolean liveFeedback) {
+		this.liveFeedback = liveFeedback;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isInterposedFeedback() {
+		return interposedFeedback;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setInterposedFeedback(final boolean interposedFeedback) {
+		this.interposedFeedback = interposedFeedback;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isLiveClicker() {
+		return liveClicker;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setLiveClicker(final boolean liveClicker) {
+		this.liveClicker = liveClicker;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isTwitterWall() {
+		return twitterWall;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setTwitterWall(final boolean twitterWall) {
+		this.twitterWall = twitterWall;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public boolean isSlides() {
+		return slides;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setSlides(final boolean slides) {
+		this.slides = slides;
+	}
+
+}

src/main/java/de/thm/arsnova/entities/SessionInfo.java → src/main/java/de/thm/arsnova/model/migration/v2/RoomInfo.java

 /*
  * This file is part of ARSnova Backend.
- * Copyright (C) 2012-2015 The ARSnova Team
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
  *
  * ARSnova Backend is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,12 +15,23 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package de.thm.arsnova.entities;
 
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
 import java.util.ArrayList;
 import java.util.List;
 
-public class SessionInfo {
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * Summary information of a specific Room. For example, this is used to display list entries of a user's Rooms as well
+ * as a user's Room History (Visited Rooms).
+ */
+@ApiModel(value = "RoomInfo", description = "Room (Session) Info entity")
+public class RoomInfo {
 
 	private String name;
 	private String shortName;
@@ -34,142 +45,176 @@ public class SessionInfo {
 
 	private int numQuestions;
 	private int numAnswers;
-	private int numInterposed;
-	private int numUnredInterposed;
+	private int numComments;
+	private int numUnreadComments;
 	private int numUnanswered;
 
-	public SessionInfo(Session session) {
-		this.name = session.getName();
-		this.shortName = session.getShortName();
-		this.keyword = session.getKeyword();
-		this.active = session.isActive();
-		this.courseType = session.getCourseType();
-		this.creationTime = session.getCreationTime();
-		this.sessionType = session.getSessionType();
-		this.ppLevel = session.getPpLevel();
-		this.ppSubject = session.getPpSubject();
+	public RoomInfo(final Room room) {
+		this.name = room.getName();
+		this.shortName = room.getShortName();
+		this.keyword = room.getKeyword();
+		this.active = room.isActive();
+		this.courseType = room.getCourseType();
+		this.creationTime = room.getCreationTime();
+		this.sessionType = room.getSessionType();
+		this.ppLevel = room.getPpLevel();
+		this.ppSubject = room.getPpSubject();
 	}
 
-	public SessionInfo() {}
+	public RoomInfo() {
+
+	}
 
-	public static List<SessionInfo> fromSessionList(List<Session> sessions) {
-		List<SessionInfo> infos = new ArrayList<SessionInfo>();
-		for (Session s : sessions) {
-			infos.add(new SessionInfo(s));
+	public static List<RoomInfo> fromSessionList(final List<Room> sessions) {
+		final List<RoomInfo> infos = new ArrayList<>();
+		for (final Room s : sessions) {
+			infos.add(new RoomInfo(s));
 		}
 		return infos;
 	}
 
+	@ApiModelProperty(required = true, value = "the name")
+	@JsonView(View.Public.class)
 	public String getName() {
 		return name;
 	}
 
-	public void setName(String name) {
+	public void setName(final String name) {
 		this.name = name;
 	}
 
+	@ApiModelProperty(required = true, value = "the short name")
+	@JsonView(View.Public.class)
 	public String getShortName() {
 		return shortName;
 	}
 
-	public void setShortName(String shortName) {
+	public void setShortName(final String shortName) {
 		this.shortName = shortName;
 	}
 
+	@ApiModelProperty(required = true, value = "the keyword")
+	@JsonView(View.Public.class)
 	public String getKeyword() {
 		return keyword;
 	}
 
-	public void setKeyword(String keyword) {
+	public void setKeyword(final String keyword) {
 		this.keyword = keyword;
 	}
 
+	@ApiModelProperty(required = true, value = "true for active")
+	@JsonView(View.Public.class)
 	public boolean isActive() {
 		return active;
 	}
 
-	public void setActive(boolean active) {
+	public void setActive(final boolean active) {
 		this.active = active;
 	}
 
+	@ApiModelProperty(required = true, value = "the source the course comes from (example: moodle)")
+	@JsonView(View.Public.class)
 	public String getCourseType() {
 		return courseType;
 	}
 
-	public void setCourseType(String courseType) {
+	public void setCourseType(final String courseType) {
 		this.courseType = courseType;
 	}
 
+	@ApiModelProperty(required = true, value = "the session type")
+	@JsonView(View.Public.class)
 	public String getSessionType() {
 		return sessionType;
 	}
 
-	public void setSessionType(String sessionType) {
+	public void setSessionType(final String sessionType) {
 		this.sessionType = sessionType;
 	}
 
+	@ApiModelProperty(required = true, value = "used to display level")
+	@JsonView(View.Public.class)
 	public String getPpLevel() {
 		return ppLevel;
 	}
 
-	public void setPpLevel(String ppLevel) {
+	public void setPpLevel(final String ppLevel) {
 		this.ppLevel = ppLevel;
 	}
 
+	@ApiModelProperty(required = true, value = "the public pool subject")
+	@JsonView(View.Public.class)
 	public String getPpSubject() {
 		return ppSubject;
 	}
 
-	public void setPpSubject(String ppSubject) {
+	public void setPpSubject(final String ppSubject) {
 		this.ppSubject = ppSubject;
 	}
 
+	@ApiModelProperty(required = true, value = "the number of questions")
+	@JsonView(View.Public.class)
 	public int getNumQuestions() {
 		return numQuestions;
 	}
 
-	public void setNumQuestions(int numQuestions) {
+	public void setNumQuestions(final int numQuestions) {
 		this.numQuestions = numQuestions;
 	}
 
+	@ApiModelProperty(required = true, value = "the number of answers")
+	@JsonView(View.Public.class)
 	public int getNumAnswers() {
 		return numAnswers;
 	}
 
-	public void setNumAnswers(int numAnswers) {
+	public void setNumAnswers(final int numAnswers) {
 		this.numAnswers = numAnswers;
 	}
 
+	/* Still named "Interposed" instead of "Comments" here for compatibilty reasons. */
+	@ApiModelProperty(required = true, value = "used to display comment number")
+	@JsonView(View.Public.class)
 	public int getNumInterposed() {
-		return numInterposed;
+		return numComments;
 	}
 
-	public void setNumInterposed(int numInterposed) {
-		this.numInterposed = numInterposed;
+	/* Still named "Interposed" instead of "Comments" here for compatibilty reasons. */
+	public void setNumInterposed(final int numComments) {
+		this.numComments = numComments;
 	}
 
+	@ApiModelProperty(required = true, value = "the number of unanswered questions")
+	@JsonView(View.Public.class)
 	public int getNumUnanswered() {
 		return numUnanswered;
 	}
 
-	public void setNumUnanswered(int numUnanswered) {
+	public void setNumUnanswered(final int numUnanswered) {
 		this.numUnanswered = numUnanswered;
 	}
 
+	@ApiModelProperty(required = true, value = "the creation timestamp")
+	@JsonView(View.Public.class)
 	public long getCreationTime() {
 		return creationTime;
 	}
 
-	public void setCreationTime(long creationTime) {
+	public void setCreationTime(final long creationTime) {
 		this.creationTime = creationTime;
 	}
 
+	/* Still named "Interposed" instead of "Comments" here for compatibilty reasons. */
+	@ApiModelProperty(required = true, value = "the number of unread comments")
+	@JsonView(View.Public.class)
 	public int getNumUnredInterposed() {
-		return numUnredInterposed;
+		return numUnreadComments;
 	}
 
-	public void setNumUnredInterposed(int numUnredInterposed) {
-		this.numUnredInterposed = numUnredInterposed;
+	/* Still named "Interposed" instead of "Comments" here for compatibilty reasons. */
+	public void setNumUnredInterposed(final int numUnreadComments) {
+		this.numUnreadComments = numUnreadComments;
 	}
 
 	@Override
@@ -182,14 +227,18 @@ public class SessionInfo {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(final Object obj) {
 		// auto generated!
-		if (this == obj) return true;
-		if (obj == null) return false;
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null) {
+			return false;
+		}
 		if (getClass() != obj.getClass()) {
 			return false;
 		}
-		SessionInfo other = (SessionInfo) obj;
+		final RoomInfo other = (RoomInfo) obj;
 		if (keyword == null) {
 			if (other.keyword != null) {
 				return false;

src/main/java/de/thm/arsnova/model/migration/v2/VisitedRoom.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.migration.v2;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonView;
+import io.swagger.annotations.ApiModel;
+
+import de.thm.arsnova.model.serialization.View;
+
+/**
+ * A Room (Session) a user has visited previously.
+ */
+@ApiModel(value = "VisitedRoom",
+		description = "Visited Room (Session) entity - An entry of the Room History for the Logged In entity")
+public class VisitedRoom {
+	@JsonProperty("_id")
+	private String id;
+	private String name;
+	private String keyword;
+
+	public VisitedRoom() {
+	}
+
+	public VisitedRoom(final Room s) {
+		this.id = s.getId();
+		this.name = s.getName();
+		this.keyword = s.getKeyword();
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getId() {
+		return id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setId(final String id) {
+		this.id = id;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getName() {
+		return name;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setName(final String name) {
+		this.name = name;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public String getKeyword() {
+		return keyword;
+	}
+
+	@JsonView({View.Persistence.class, View.Public.class})
+	public void setKeyword(final String keyword) {
+		this.keyword = keyword;
+	}
+
+	@Override
+	public String toString() {
+		return "VisitedRoom [id=" + id + ", name=" + name + ", keyword="
+				+ keyword + "]";
+	}
+}

src/main/java/de/thm/arsnova/model/package-info.java

+/**
+ * Classes to translate objects to and from JSON.
+ */
+
+package de.thm.arsnova.model;

src/main/java/de/thm/arsnova/model/serialization/CouchDbDocumentMixIn.java

+/*
+ * This file is part of ARSnova Backend.
+ * Copyright (C) 2012-2019 The ARSnova Team and Contributors
+ *
+ * ARSnova Backend is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova Backend is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.model.serialization;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+import de.thm.arsnova.model.Entity;
+
+@JsonIgnoreProperties(value = {"type"}, allowGetters = true)
+public abstract class CouchDbDocumentMixIn {
+	@JsonProperty("_id")
+	@JsonInclude(JsonInclude.Include.NON_EMPTY)
+	abstract String getId();
+
+	@JsonProperty("_id")
+	abstract void setId(String id);
+
+	@JsonProperty("_rev")
+	@JsonInclude(JsonInclude.Include.NON_EMPTY)
+	abstract String getRevision();
+
+	@JsonProperty("_rev")
+	abstract String setRevision(String rev);
+
+	@JsonSerialize(converter = CouchDbTypeFieldConverter.class)
+	abstract Class<? extends Entity> getType();
+}