Separate content persistance code and migrate it to Ektorp

(Lecturer/Skill)Question has been renamed to Content. Method names have
not been touched yet to ease reviewing the changes.

src/main/java/de/thm/arsnova/cache/CacheBuster.java

@@ -51,7 +51,7 @@ public class CacheBuster implements ICacheBuster, NovaEventVisitor {
 	@Override
 	public void visit(LockQuestionsEvent lockQuestionsEvent) { }
 
-	@CacheEvict(value = "answers", key = "#event.Question")
+	@CacheEvict(value = "answers", key = "#event.content")
 	@Override
 	public void visit(NewAnswerEvent event) { }
 

src/main/java/de/thm/arsnova/config/AppConfig.java

@@ -27,16 +27,19 @@ import de.thm.arsnova.entities.Comment;
 import de.thm.arsnova.entities.DbUser;
 import de.thm.arsnova.entities.LogEntry;
 import de.thm.arsnova.entities.Motd;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 import de.thm.arsnova.entities.serialization.CouchDbDocumentModule;
 import de.thm.arsnova.entities.serialization.CouchDbObjectMapperFactory;
 import de.thm.arsnova.entities.serialization.View;
 import de.thm.arsnova.persistance.CommentRepository;
+import de.thm.arsnova.persistance.ContentRepository;
 import de.thm.arsnova.persistance.LogEntryRepository;
 import de.thm.arsnova.persistance.MotdRepository;
 import de.thm.arsnova.persistance.SessionRepository;
 import de.thm.arsnova.persistance.UserRepository;
 import de.thm.arsnova.persistance.couchdb.CouchDbCommentRepository;
+import de.thm.arsnova.persistance.couchdb.CouchDbContentRepository;
 import de.thm.arsnova.persistance.couchdb.CouchDbLogEntryRepository;
 import de.thm.arsnova.persistance.couchdb.CouchDbMotdRepository;
 import de.thm.arsnova.persistance.couchdb.CouchDbSessionRepository;
@@ -300,6 +303,11 @@ public class AppConfig extends WebMvcConfigurerAdapter {
 		return new CouchDbCommentRepository(Comment.class, couchDbConnector(), false);
 	}
 
+	@Bean
+	public ContentRepository contentRepository() throws Exception {
+		return new CouchDbContentRepository(Content.class, couchDbConnector(), false);
+	}
+
 	@Bean
 	public UserRepository userRepository() throws Exception {
 		return new CouchDbUserRepository(DbUser.class, couchDbConnector(), false);

src/main/java/de/thm/arsnova/controller/CommentController.java

@@ -20,7 +20,7 @@ package de.thm.arsnova.controller;
 import de.thm.arsnova.entities.CommentReadingCount;
 import de.thm.arsnova.entities.transport.Comment;
 import de.thm.arsnova.exceptions.BadRequestException;
-import de.thm.arsnova.services.IQuestionService;
+import de.thm.arsnova.services.IContentService;
 import de.thm.arsnova.web.DeprecatedApi;
 import de.thm.arsnova.web.Pagination;
 import io.swagger.annotations.Api;
@@ -45,11 +45,11 @@ import java.util.List;
  */
 @RestController
 @RequestMapping("/audiencequestion")
-@Api(value = "/audiencequestion", description = "the Audience Question API")
+@Api(value = "/audiencequestion", description = "the Audience Content API")
 public class CommentController extends PaginationController {
 
 	@Autowired
-	private IQuestionService questionService;
+	private IContentService contentService;
 
 	@ApiOperation(value = "Count all the comments in current session",
 			nickname = "getAudienceQuestionCount")
@@ -57,7 +57,7 @@ public class CommentController extends PaginationController {
 	@DeprecatedApi
 	@Deprecated
 	public int getInterposedCount(@ApiParam(value = "Session-Key from current session", required = true) @RequestParam final String sessionkey) {
-		return questionService.getInterposedCount(sessionkey);
+		return contentService.getInterposedCount(sessionkey);
 	}
 
 	@ApiOperation(value = "count all unread comments",
@@ -66,7 +66,7 @@ public class CommentController extends PaginationController {
 	@DeprecatedApi
 	@Deprecated
 	public CommentReadingCount getUnreadInterposedCount(@ApiParam(value = "Session-Key from current session", required = true) @RequestParam("sessionkey") final String sessionkey, String user) {
-		return questionService.getInterposedReadingCount(sessionkey, user);
+		return contentService.getInterposedReadingCount(sessionkey, user);
 	}
 
 	@ApiOperation(value = "Retrieves all Comments for a Session",
@@ -74,14 +74,14 @@ public class CommentController extends PaginationController {
 	@RequestMapping(value = "/", method = RequestMethod.GET)
 	@Pagination
 	public List<Comment> getInterposedQuestions(@ApiParam(value = "Session-Key from current session", required = true) @RequestParam final String sessionkey) {
-		return Comment.fromList(questionService.getInterposedQuestions(sessionkey, offset, limit));
+		return Comment.fromList(contentService.getInterposedQuestions(sessionkey, offset, limit));
 	}
 
 	@ApiOperation(value = "Retrieves an Comment",
 			nickname = "getInterposedQuestion")
 	@RequestMapping(value = "/{questionId}", method = RequestMethod.GET)
 	public Comment getInterposedQuestion(@ApiParam(value = "ID of the Comment that needs to be deleted", required = true) @PathVariable final String questionId) {
-		return new Comment(questionService.readInterposedQuestion(questionId));
+		return new Comment(contentService.readInterposedQuestion(questionId));
 	}
 
 	@ApiOperation(value = "Creates a new Comment for a Session and returns the Comment's data",
@@ -95,7 +95,7 @@ public class CommentController extends PaginationController {
 			@ApiParam(value = "Session-Key from current session", required = true) @RequestParam final String sessionkey,
 			@ApiParam(value = "the body from the new comment", required = true) @RequestBody final de.thm.arsnova.entities.Comment comment
 			) {
-		if (questionService.saveQuestion(comment)) {
+		if (contentService.saveQuestion(comment)) {
 			return;
 		}
 
@@ -106,6 +106,6 @@ public class CommentController extends PaginationController {
 			nickname = "deleteInterposedQuestion")
 	@RequestMapping(value = "/{questionId}", method = RequestMethod.DELETE)
 	public void deleteInterposedQuestion(@ApiParam(value = "ID of the comment that needs to be deleted", required = true) @PathVariable final String questionId) {
-		questionService.deleteInterposedQuestion(questionId);
+		contentService.deleteInterposedQuestion(questionId);
 	}
 }

src/main/java/de/thm/arsnova/controller/LegacyController.java

@@ -17,7 +17,7 @@
  */
 package de.thm.arsnova.controller;
 
-import de.thm.arsnova.services.IQuestionService;
+import de.thm.arsnova.services.IContentService;
 import de.thm.arsnova.web.DeprecatedApi;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
@@ -33,7 +33,7 @@ import org.springframework.web.bind.annotation.ResponseBody;
 public class LegacyController extends AbstractController {
 
 	@Autowired
-	private IQuestionService questionService;
+	private IContentService contentService;
 
 	/* specific routes */
 
@@ -95,7 +95,7 @@ public class LegacyController extends AbstractController {
 	@RequestMapping(value = "/session/{sessionKey}/interposed", method = RequestMethod.DELETE)
 	@ResponseBody
 	public void deleteAllInterposedQuestions(@PathVariable final String sessionKey) {
-		questionService.deleteAllInterposedQuestions(sessionKey);
+		contentService.deleteAllInterposedQuestions(sessionKey);
 	}
 
 	@DeprecatedApi

src/main/java/de/thm/arsnova/dao/IDatabaseDao.java

@@ -26,35 +26,17 @@ import java.util.List;
  * All methods the database must support.
  */
 public interface IDatabaseDao {
-	Question saveQuestion(Session session, Question question);
-
-	Question getQuestion(String id);
-
-	List<Question> getSkillQuestionsForUsers(Session session);
-
-	List<Question> getSkillQuestionsForTeachers(Session session);
-
-	int getSkillQuestionCount(Session session);
-
-	List<String> getQuestionIds(Session session, User user);
-
-	int deleteQuestionWithAnswers(Question question);
-
-	int[] deleteAllQuestionsWithAnswers(Session session);
-
-	List<String> getUnAnsweredQuestionIds(Session session, User user);
-
 	Answer getMyAnswer(User me, String questionId, int piRound);
 
-	List<Answer> getAnswers(Question question, int piRound);
+	List<Answer> getAnswers(Content content, int piRound);
 
-	List<Answer> getAnswers(Question question);
+	List<Answer> getAnswers(Content content);
 
-	List<Answer> getAllAnswers(Question question);
+	List<Answer> getAllAnswers(Content content);
 
-	int getAnswerCount(Question question, int piRound);
+	int getAnswerCount(Content content, int piRound);
 
-	int getTotalAnswerCountByQuestion(Question question);
+	int getTotalAnswerCountByQuestion(Content content);
 
 	int getAbstentionAnswerCount(String questionId);
 
@@ -64,11 +46,9 @@ public interface IDatabaseDao {
 
 	int getTotalAnswerCount(String sessionKey);
 
-	Question updateQuestion(Question question);
+	int deleteAnswers(Content content);
 
-	int deleteAnswers(Question question);
-
-	Answer saveAnswer(Answer answer, User user, Question question, Session session);
+	Answer saveAnswer(Answer answer, User user, Content content, Session session);
 
 	Answer updateAnswer(Answer answer);
 
@@ -76,44 +56,10 @@ public interface IDatabaseDao {
 
 	int deleteInactiveGuestVisitedSessionLists(long lastActivityBefore);
 
-	List<Question> getLectureQuestionsForUsers(Session session);
-
-	List<Question> getLectureQuestionsForTeachers(Session session);
-
-	List<Question> getFlashcardsForUsers(Session session);
-
-	List<Question> getFlashcardsForTeachers(Session session);
-
-	List<Question> getPreparationQuestionsForUsers(Session session);
-
-	List<Question> getPreparationQuestionsForTeachers(Session session);
-
-	List<Question> getAllSkillQuestions(Session session);
-
-	int getLectureQuestionCount(Session session);
-
-	int getFlashcardCount(Session session);
-
-	int getPreparationQuestionCount(Session session);
-
 	int countLectureQuestionAnswers(Session session);
 
 	int countPreparationQuestionAnswers(Session session);
 
-	int[] deleteAllLectureQuestionsWithAnswers(Session session);
-
-	int[] deleteAllFlashcardsWithAnswers(Session session);
-
-	int[] deleteAllPreparationQuestionsWithAnswers(Session session);
-
-	List<String> getUnAnsweredLectureQuestionIds(Session session, User user);
-
-	List<String> getUnAnsweredPreparationQuestionIds(Session session, User user);
-
-	void publishQuestions(Session session, boolean publish, List<Question> questions);
-
-	List<Question> publishAllQuestions(Session session, boolean publish);
-
 	int deleteAllQuestionsAnswers(Session session);
 
 	CourseScore getLearningProgress(Session session);
@@ -124,21 +70,11 @@ public interface IDatabaseDao {
 
 	Statistics getStatistics();
 
-	List<String> getSubjects(Session session, String questionVariant);
-
-	List<String> getQuestionIdsBySubject(Session session, String questionVariant, String subject);
-
-	List<Question> getQuestionsByIds(List<String> ids, Session session);
-
-	void resetQuestionsRoundState(Session session, List<Question> questions);
-
-	void setVotingAdmissions(Session session, boolean disableVoting, List<Question> questions);
-
-	List<Question> setVotingAdmissionForAllQuestions(Session session, boolean disableVoting);
-
 	<T> T getObjectFromId(String documentId, Class<T> klass);
 
 	MotdList getMotdListForUser(final String username);
 
 	MotdList createOrUpdateMotdList(MotdList motdlist);
+
+	int[] deleteAllAnswersWithQuestions(List<Content> contents);
 }

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

@@ -17,20 +17,21 @@
  */
 package de.thm.arsnova.entities;
 
+import com.fasterxml.jackson.annotation.JsonView;
+import de.thm.arsnova.entities.serialization.View;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
 
-import java.io.Serializable;
 import java.util.Date;
 import java.util.List;
 
 /**
  * A question the teacher is asking.
  */
-@ApiModel(value = "lecturerquestion", description = "the question entity")
-public class Question implements Serializable {
-
-	private String type;
+@ApiModel(value = "content", description = "the content entity")
+public class Content implements Entity {
+	private String id;
+	private String rev;
 	private String questionType;
 	private String questionVariant;
 	private String subject;
@@ -62,8 +63,6 @@ public class Question implements Serializable {
 	private boolean strictMode;
 	private int rating;
 	private String correctAnswer;
-	private String _id;
-	private String _rev;
 
 	private String image;
 	private String fcImage;
@@ -92,56 +91,78 @@ public class Question implements Serializable {
 	private String hint;
 	private String solution;
 
-	@ApiModelProperty(required = true, value = "the type")
-	public final String getType() {
-		return type;
+	@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;
 	}
 
-	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;
 	}
@@ -156,10 +177,12 @@ public class Question implements Serializable {
 	}
 
 	@ApiModelProperty(required = true, value = "list of possible answers")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final List<PossibleAnswer> getPossibleAnswers() {
 		return possibleAnswers;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public final void setPossibleAnswers(final List<PossibleAnswer> possibleAnswers) {
 		this.possibleAnswers = possibleAnswers;
 	}
@@ -174,10 +197,12 @@ public class Question implements Serializable {
 	}
 
 	@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;
 	}
@@ -201,10 +226,12 @@ public class Question implements Serializable {
 	}
 
 	@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;
 	}
@@ -219,46 +246,56 @@ public class Question implements Serializable {
 	}
 
 	@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(boolean imageQuestion) {
 		this.imageQuestion = imageQuestion;
 	}
 
-	public final void setDuration(final int duration) {
-		this.duration = duration;
-	}
-
 	@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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPiRoundEndTime(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setPiRoundStartTime(long piRoundStartTime) {
 		this.piRoundStartTime = piRoundStartTime;
 	}
@@ -282,340 +319,395 @@ public class Question implements Serializable {
 	}
 
 	@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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setCvIsColored(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;
 	}
 
+	@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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setIgnorePunctuation(final boolean ignorePunctuation) {
 		this.ignorePunctuation = ignorePunctuation;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public boolean isFixedAnswer() {
 		return this.fixedAnswer;
 	}
 
+	@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 couchDB ID")
-	public final String get_id() {
-		return _id;
-	}
-
-	public final void set_id(final String _id) {
-		this._id = _id;
-	}
-
-	public final String get_rev() {
-		return _rev;
-	}
-
-	public final void set_rev(final String _rev) {
-		this._rev = _rev;
-	}
-
 	@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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridOffsetX(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridOffsetY(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridZoomLvl(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridSizeX(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridSizeY(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridIsHidden(boolean gridIsHidden) {
 		this.gridIsHidden = gridIsHidden;
 	}
 
 	@ApiModelProperty(required = true, value = "the image rotation")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public int getImgRotation() {
 		return imgRotation;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setImgRotation(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setToggleFieldsLeft(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setNumClickableFields(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setThresholdCorrectAnswers(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridLineColor(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setNumberOfDots(int numberOfDots) {
 		this.numberOfDots = numberOfDots;
 	}
 
 	@ApiModelProperty(required = true, value = "the grid type")
+	@JsonView({View.Persistence.class, View.Public.class})
 	public String getGridType() {
 		return gridType;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridType(String gridType) {
 		this.gridType = gridType;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setScaleFactor(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;
 	}
 
+	@JsonView({View.Persistence.class, View.Public.class})
 	public void setGridScaleFactor(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(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(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(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(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
@@ -623,7 +715,7 @@ public class Question implements Serializable {
 		// auto generated!
 		final int prime = 31;
 		int result = 1;
-		result = prime * result + ((_id == null) ? 0 : _id.hashCode());
+		result = prime * result + ((id == null) ? 0 : id.hashCode());
 		return result;
 	}
 
@@ -639,12 +731,12 @@ public class Question implements Serializable {
 		if (getClass() != obj.getClass()) {
 			return false;
 		}
-		Question other = (Question) obj;
-		if (_id == null) {
-			if (other._id != null) {
+		Content other = (Content) obj;
+		if (id == null) {
+			if (other.id != null) {
 				return false;
 			}
-		} else if (!_id.equals(other._id)) {
+		} else if (!id.equals(other.id)) {
 			return false;
 		}
 		return true;

src/main/java/de/thm/arsnova/entities/PossibleAnswer.java

@@ -17,6 +17,8 @@
  */
 package de.thm.arsnova.entities;
 
+import com.fasterxml.jackson.annotation.JsonView;
+import de.thm.arsnova.entities.serialization.View;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
 
@@ -43,28 +45,34 @@ public class PossibleAnswer implements Serializable {
 	}
 
 	@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(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(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(int value) {
 		this.value = value;
 	}

src/main/java/de/thm/arsnova/entities/serialization/CouchDbTypeFieldConverter.java

@@ -25,6 +25,7 @@ import de.thm.arsnova.entities.DbUser;
 import de.thm.arsnova.entities.Entity;
 import de.thm.arsnova.entities.LogEntry;
 import de.thm.arsnova.entities.Motd;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
@@ -39,6 +40,7 @@ public class CouchDbTypeFieldConverter implements Converter<Class<? extends Enti
 		typeMapping.put(Motd.class, "motd");
 		typeMapping.put(Session.class, "session");
 		typeMapping.put(Comment.class, "interposed_question");
+		typeMapping.put(Content.class, "skill_question");
 	}
 
 	@Override

src/main/java/de/thm/arsnova/entities/transport/Answer.java

@@ -19,7 +19,7 @@ package de.thm.arsnova.entities.transport;
 
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonView;
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.User;
 import de.thm.arsnova.entities.serialization.View;
 import io.swagger.annotations.ApiModel;
@@ -126,28 +126,28 @@ public class Answer implements Serializable {
 		this.abstention = abstention;
 	}
 
-	public de.thm.arsnova.entities.Answer generateAnswerEntity(final User user, final Question question) {
+	public de.thm.arsnova.entities.Answer generateAnswerEntity(final User user, final Content content) {
 		// rewrite all fields so that no manipulated data gets written
 		// only answerText, answerSubject, and abstention are allowed
 		de.thm.arsnova.entities.Answer theAnswer = new de.thm.arsnova.entities.Answer();
 		theAnswer.setAnswerSubject(this.getAnswerSubject());
 		theAnswer.setAnswerText(this.getAnswerText());
 		theAnswer.setAnswerTextRaw(this.getAnswerTextRaw());
-		theAnswer.setSessionId(question.getSessionId());
+		theAnswer.setSessionId(content.getSessionId());
 		theAnswer.setUser(user.getUsername());
-		theAnswer.setQuestionId(question.get_id());
+		theAnswer.setQuestionId(content.getId());
 		theAnswer.setTimestamp(new Date().getTime());
-		theAnswer.setQuestionVariant(question.getQuestionVariant());
+		theAnswer.setQuestionVariant(content.getQuestionVariant());
 		theAnswer.setAbstention(this.isAbstention());
 		// calculate learning progress value after all properties are set
-		theAnswer.setQuestionValue(question.calculateValue(theAnswer));
+		theAnswer.setQuestionValue(content.calculateValue(theAnswer));
 		theAnswer.setAnswerImage(this.getAnswerImage());
 		theAnswer.setSuccessfulFreeTextAnswer(this.isSuccessfulFreeTextAnswer());
 
-		if ("freetext".equals(question.getQuestionType())) {
+		if ("freetext".equals(content.getQuestionType())) {
 			theAnswer.setPiRound(0);
 		} else {
-			theAnswer.setPiRound(question.getPiRound());
+			theAnswer.setPiRound(content.getPiRound());
 		}
 
 		return theAnswer;

src/main/java/de/thm/arsnova/entities/transport/AnswerQueueElement.java

@@ -18,7 +18,7 @@
 package de.thm.arsnova.entities.transport;
 
 import de.thm.arsnova.entities.Answer;
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 import de.thm.arsnova.entities.User;
 
@@ -30,15 +30,15 @@ public class AnswerQueueElement {
 
 	private final Session session;
 
-	private final Question question;
+	private final Content content;
 
 	private final Answer answer;
 
 	private final User user;
 
-	public AnswerQueueElement(Session session, Question question, Answer answer, User user) {
+	public AnswerQueueElement(Session session, Content content, Answer answer, User user) {
 		this.session = session;
-		this.question = question;
+		this.content = content;
 		this.answer = answer;
 		this.user = user;
 	}
@@ -47,8 +47,8 @@ public class AnswerQueueElement {
 		return session;
 	}
 
-	public Question getQuestion() {
-		return question;
+	public Content getQuestion() {
+		return content;
 	}
 
 	public Answer getAnswer() {

src/main/java/de/thm/arsnova/entities/transport/ImportExportSession.java

@@ -18,8 +18,8 @@
 package de.thm.arsnova.entities.transport;
 
 import com.fasterxml.jackson.annotation.JsonView;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Motd;
-import de.thm.arsnova.entities.Question;
 import de.thm.arsnova.entities.Session;
 import de.thm.arsnova.entities.SessionFeature;
 import de.thm.arsnova.entities.SessionInfo;
@@ -40,7 +40,7 @@ public class ImportExportSession {
 
 	private ImportExportSesssion session;
 
-	private List<ImportExportQuestion> questions;
+	private List<ImportExportContent> questions;
 
 	private List<Comment> feedbackQuestions;
 
@@ -69,11 +69,11 @@ public class ImportExportSession {
 
 	@ApiModelProperty(required = true, value = "used to display questions")
 	@JsonView(View.Public.class)
-	public List<ImportExportQuestion> getQuestions() {
+	public List<ImportExportContent> getQuestions() {
 		return questions;
 	}
 
-	public void setQuestions(List<ImportExportQuestion> questions) {
+	public void setQuestions(List<ImportExportContent> questions) {
 		this.questions = questions;
 	}
 
@@ -126,8 +126,8 @@ public class ImportExportSession {
 		session = iesession;
 	}
 
-	public void addQuestionWithAnswers(Question q, List<Answer> aL) {
-		ImportExportQuestion ieq = new ImportExportQuestion(q);
+	public void addQuestionWithAnswers(Content q, List<Answer> aL) {
+		ImportExportContent ieq = new ImportExportContent(q);
 		ieq.setAnswers(aL);
 		questions.add(ieq);
 	}
@@ -158,16 +158,15 @@ public class ImportExportSession {
 		return s;
 	}
 
-	public static class ImportExportQuestion extends Question {
+	public static class ImportExportContent extends Content {
 
 		private List<Answer> answers;
 
-		public ImportExportQuestion() {
+		public ImportExportContent() {
 
 		}
 
-		public ImportExportQuestion(Question q) {
-			setType(q.getType());
+		public ImportExportContent(Content q) {
 			setQuestionType(q.getQuestionType());
 			setQuestionVariant(q.getQuestionVariant());
 			setSubject(q.getSubject());

src/main/java/de/thm/arsnova/events/DeleteAnswerEvent.java

@@ -17,7 +17,7 @@
  */
 package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 /**
@@ -27,11 +27,11 @@ public class DeleteAnswerEvent extends SessionEvent {
 
 	private static final long serialVersionUID = 1L;
 
-	private final Question question;
+	private final Content content;
 
-	public DeleteAnswerEvent(Object source, Session session, Question question) {
+	public DeleteAnswerEvent(Object source, Session session, Content content) {
 		super(source, session);
-		this.question = question;
+		this.content = content;
 	}
 
 	@Override
@@ -39,7 +39,7 @@ public class DeleteAnswerEvent extends SessionEvent {
 		visitor.visit(this);
 	}
 
-	public Question getQuestion() {
-		return question;
+	public Content getQuestion() {
+		return content;
 	}
 }

src/main/java/de/thm/arsnova/events/DeleteQuestionEvent.java

@@ -17,25 +17,25 @@
  */
 package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 /**
- * Fires whenever a question is deleted.
+ * Fires whenever a content is deleted.
  */
 public class DeleteQuestionEvent extends SessionEvent {
 
 	private static final long serialVersionUID = 1L;
 
-	private final Question question;
+	private final Content content;
 
-	public DeleteQuestionEvent(Object source, Session session, Question question) {
+	public DeleteQuestionEvent(Object source, Session session, Content content) {
 		super(source, session);
-		this.question = question;
+		this.content = content;
 	}
 
-	public Question getQuestion() {
-		return this.question;
+	public Content getQuestion() {
+		return this.content;
 	}
 
 	@Override

src/main/java/de/thm/arsnova/events/LockQuestionEvent.java

@@ -17,25 +17,25 @@
  */
 package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 /**
- * Fires whenever a question is disabled, i.e., it is hidden from students.
+ * Fires whenever a content is disabled, i.e., it is hidden from students.
  */
 public class LockQuestionEvent extends SessionEvent {
 
 	private static final long serialVersionUID = 1L;
 
-	private final Question question;
+	private final Content content;
 
-	public LockQuestionEvent(Object source, Session session, Question question) {
+	public LockQuestionEvent(Object source, Session session, Content content) {
 		super(source, session);
-		this.question = question;
+		this.content = content;
 	}
 
-	public Question getQuestion() {
-		return this.question;
+	public Content getQuestion() {
+		return this.content;
 	}
 
 	@Override

src/main/java/de/thm/arsnova/events/LockQuestionsEvent.java

@@ -17,27 +17,27 @@
  */
 package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 import java.util.List;
 
 /**
- * Fires whenever a set of questions are disabled, i.e., they are hidden from students.
+ * Fires whenever a set of contents are disabled, i.e., they are hidden from students.
  */
 public class LockQuestionsEvent extends SessionEvent {
 
 	private static final long serialVersionUID = 1L;
 
-	private List<Question> questions;
+	private List<Content> contents;
 
-	public LockQuestionsEvent(Object source, Session session, List<Question> questions) {
+	public LockQuestionsEvent(Object source, Session session, List<Content> contents) {
 		super(source, session);
-		this.questions = questions;
+		this.contents = contents;
 	}
 
-	public List<Question> getQuestions() {
-		return this.questions;
+	public List<Content> getQuestions() {
+		return this.contents;
 	}
 
 	@Override

src/main/java/de/thm/arsnova/events/LockVoteEvent.java

@@ -17,36 +17,36 @@
  */
 package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
 import java.util.Map;
 
 /**
- * Fires whenever voting on a question is disabled.
+ * Fires whenever voting on a content is disabled.
  */
 public class LockVoteEvent extends SessionEvent {
 
 	private static final long serialVersionUID = 1L;
 
-	private final Question question;
+	private final Content content;
 
-	public LockVoteEvent(Object source, Session session, Question question) {
+	public LockVoteEvent(Object source, Session session, Content content) {
 		super(source, session);
-		this.question = question;
+		this.content = content;
 	}
 
 	public String getQuestionId() {
-		return this.question.get_id();
+		return this.content.getId();
 	}
 
 	public String getQuestionVariant() {
-		return this.question.getQuestionVariant();
+		return this.content.getQuestionVariant();
 	}
 
 	public Boolean getVotingDisabled() {
-		return this.question.isVotingDisabled();
+		return this.content.isVotingDisabled();
 	}
 
 	public Map<String, Object> getVotingAdmission() {

src/main/java/de/thm/arsnova/events/LockVotesEvent.java

@@ -17,27 +17,27 @@
  */
 package de.thm.arsnova.events;
 
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 
 import java.util.List;
 
 /**
- * Fires whenever voting of multiple questions is disabled.
+ * Fires whenever voting of multiple contents is disabled.
  */
 public class LockVotesEvent extends SessionEvent {
 
 	private static final long serialVersionUID = 1L;
 
-	private List<Question> questions;
+	private List<Content> contents;
 
-	public LockVotesEvent(Object source, Session session, List<Question> questions) {
+	public LockVotesEvent(Object source, Session session, List<Content> contents) {
 		super(source, session);
-		this.questions = questions;
+		this.contents = contents;
 	}
 
-	public List<Question> getQuestions() {
-		return this.questions;
+	public List<Content> getQuestions() {
+		return this.contents;
 	}
 
 	@Override

src/main/java/de/thm/arsnova/events/NewAnswerEvent.java

@@ -18,7 +18,7 @@
 package de.thm.arsnova.events;
 
 import de.thm.arsnova.entities.Answer;
-import de.thm.arsnova.entities.Question;
+import de.thm.arsnova.entities.Content;
 import de.thm.arsnova.entities.Session;
 import de.thm.arsnova.entities.User;
 
@@ -33,13 +33,13 @@ public class NewAnswerEvent extends SessionEvent {
 
 	private final User user;
 
-	private final Question question;
+	private final Content content;
 
-	public NewAnswerEvent(Object source, Session session, Answer answer, User user, Question question) {
+	public NewAnswerEvent(Object source, Session session, Answer answer, User user, Content content) {
 		super(source, session);
 		this.answer = answer;
 		this.user = user;
-		this.question = question;
+		this.content = content;
 	}
 
 	@Override
@@ -55,7 +55,7 @@ public class NewAnswerEvent extends SessionEvent {
 		return user;
 	}
 
-	public Question getQuestion() {
-		return question;
+	public Content getContent() {
+		return content;
 	}
 }