diff --git a/src/app/components/creator/content-choice-creator/content-choice-creator.component.ts b/src/app/components/creator/content-choice-creator/content-choice-creator.component.ts
index 0b1d6f577b62bd3d0ed115b28862a3ff03a1e736..75ae984940ca84e4b9347b72e67673c612051683 100644
--- a/src/app/components/creator/content-choice-creator/content-choice-creator.component.ts
+++ b/src/app/components/creator/content-choice-creator/content-choice-creator.component.ts
@@ -288,8 +288,8 @@ export class ContentChoiceCreatorComponent implements OnInit {
       contentGroup = this.contentCol;
     }
     this.contentService.addContent(new ContentChoice(
-      '',
-      '',
+      null,
+      null,
       this.roomId,
       this.contentSub,
       this.contentBod,
diff --git a/src/app/components/creator/content-likert-creator/content-likert-creator.component.ts b/src/app/components/creator/content-likert-creator/content-likert-creator.component.ts
index 88f54ea9e42ef19c56e3a96f5a0e38d6df8ecc61..9dc7e9a4e8f54d73540877fbb7bed54368ac9e01 100644
--- a/src/app/components/creator/content-likert-creator/content-likert-creator.component.ts
+++ b/src/app/components/creator/content-likert-creator/content-likert-creator.component.ts
@@ -98,8 +98,8 @@ export class ContentLikertCreatorComponent implements OnInit {
       contentGroup = this.contentCol;
     }
     this.contentService.addContent(new ContentChoice(
-      '',
-      '',
+      null,
+      null,
       this.roomId,
       this.contentSub,
       this.contentBod,
diff --git a/src/app/components/creator/content-yes-no-creator/content-yes-no-creator.component.ts b/src/app/components/creator/content-yes-no-creator/content-yes-no-creator.component.ts
index 93d926fdea3061f0221b2ee58ec8e13a79b1e48e..790855e948c86fd824a9f1350c32cc867d198f70 100644
--- a/src/app/components/creator/content-yes-no-creator/content-yes-no-creator.component.ts
+++ b/src/app/components/creator/content-yes-no-creator/content-yes-no-creator.component.ts
@@ -98,8 +98,8 @@ export class ContentYesNoCreatorComponent implements OnInit {
       contentGroup = this.contentCol;
     }
     this.contentService.addContent(new ContentChoice(
-      '',
-      '',
+      null,
+      null,
       this.roomId,
       this.contentSub,
       this.contentBod,
diff --git a/src/app/components/participant/comment-create-page/comment-create-page.component.ts b/src/app/components/participant/comment-create-page/comment-create-page.component.ts
index ef80b582adebf1f03b83d85d6c756c27364512ac..9dafaa1af7882b5a6005f7ea8772ab4ae0188a45 100644
--- a/src/app/components/participant/comment-create-page/comment-create-page.component.ts
+++ b/src/app/components/participant/comment-create-page/comment-create-page.component.ts
@@ -35,6 +35,8 @@ export class CommentCreatePageComponent implements OnInit {
     this.roomId = localStorage.getItem(`roomId`);
   }
 
+  // TODO: check if empty
+
   send(subject: string, body: string): void {
     subject = subject.trim();
     body = body.trim();