diff --git a/backend/src/resolvers/comments.js b/backend/src/resolvers/comments.js
index eb792ecb8..d4775b235 100644
--- a/backend/src/resolvers/comments.js
+++ b/backend/src/resolvers/comments.js
@@ -2,18 +2,41 @@ import { neo4jgraphql } from 'neo4j-graphql-js'
 import { UserInputError } from 'apollo-server'
 
 const COMMENT_MIN_LENGTH = 1
+const NO_POST_ERR_MESSAGE = 'Comment cannot be created without a post!'
+
 export default {
   Mutation: {
     CreateComment: async (object, params, context, resolveInfo) => {
       const content = params.content.replace(/<(?:.|\n)*?>/gm, '').trim()
+      const { postId } = params
+      // Adding relationship from comment to post by passing in the postId,
+      // but we do not want to create the comment with postId as an attribute
+      // because we use relationships for this. So, we are deleting it from params
+      // before comment creation.
+      delete params.postId
 
       if (!params.content || content.length < COMMENT_MIN_LENGTH) {
         throw new UserInputError(`Comment must be at least ${COMMENT_MIN_LENGTH} character long!`)
       }
-      const { postId } = params
-      const comment = await neo4jgraphql(object, params, context, resolveInfo, false)
+      if (!postId.trim()) {
+        throw new UserInputError(NO_POST_ERR_MESSAGE)
+      }
 
       const session = context.driver.session()
+      const postQueryRes = await session.run(`
+        MATCH (post:Post {id: $postId})
+        RETURN post`, {
+        postId
+      }
+      )
+      const [post] = postQueryRes.records.map(record => {
+        return record.get('post')
+      })
+
+      if (!post) {
+        throw new UserInputError(NO_POST_ERR_MESSAGE)
+      }
+      const comment = await neo4jgraphql(object, params, context, resolveInfo, false)
 
       await session.run(`
         MATCH (post:Post {id: $postId}), (comment:Comment {id: $commentId}), (author:User {id: $userId})
diff --git a/backend/src/resolvers/comments.spec.js b/backend/src/resolvers/comments.spec.js
index 9a54acd17..87a0df270 100644
--- a/backend/src/resolvers/comments.spec.js
+++ b/backend/src/resolvers/comments.spec.js
@@ -6,6 +6,8 @@ const factory = Factory()
 let client
 let createCommentVariables
 let createPostVariables
+let createCommentVariablesSansPostId
+let createCommentVariablesWithNonExistentPost
 
 beforeEach(async () => {
   await factory.create('User', {
@@ -34,6 +36,13 @@ describe('CreateComment', () => {
     }
   }
   `
+  const commentQueryForPostId = `
+    query($content: String) {
+      Comment(content: $content) {
+        postId
+      }
+    }
+  `
   describe('unauthenticated', () => {
     it('throws authorization error', async () => {
       createCommentVariables = {
@@ -54,6 +63,12 @@ describe('CreateComment', () => {
         postId: 'p1',
         content: 'I\'m authorised to comment'
       }
+      createPostVariables = {
+        id: 'p1',
+        title: 'post to comment on',
+        content: 'please comment on me'
+      }
+      await client.request(createPostMutation, createPostVariables)
     })
 
     it('creates a comment', async () => {
@@ -67,12 +82,6 @@ describe('CreateComment', () => {
     })
 
     it('assigns the authenticated user as author', async () => {
-      createPostVariables = {
-        id: 'p1',
-        title: 'post to comment on',
-        content: 'please comment on me'
-      }
-      await client.request(createPostMutation, createPostVariables)
       await client.request(createCommentMutation, createCommentVariables)
 
       const { User } = await client.request(`{
@@ -86,7 +95,7 @@ describe('CreateComment', () => {
       expect(User).toEqual([ { comments: [ { content: 'I\'m authorised to comment' } ] } ])
     })
 
-    it('throw an error if an empty string is sent as content', async () => {
+    it('throw an error if an empty string is sent from the editor as content', async () => {
       createCommentVariables = {
         postId: 'p1',
         content: '<p></p>'
@@ -96,7 +105,7 @@ describe('CreateComment', () => {
         .rejects.toThrow('Comment must be at least 1 character long!')
     })
 
-    it('throws an error if a comment does not contain a single character', async () => {
+    it('throws an error if a comment sent from the editor does not contain a single character', async () => {
       createCommentVariables = {
         postId: 'p1',
         content: '<p> </p>'
@@ -105,5 +114,65 @@ describe('CreateComment', () => {
       await expect(client.request(createCommentMutation, createCommentVariables))
         .rejects.toThrow('Comment must be at least 1 character long!')
     })
+
+    it('throws an error if postId is sent as an empty string', async () => {
+      createCommentVariables = {
+        postId: 'p1',
+        content: ''
+      }
+
+      await expect(client.request(createCommentMutation, createCommentVariables))
+        .rejects.toThrow('Comment must be at least 1 character long!')
+    })
+
+    it('throws an error if content is sent as an string of empty characters', async () => {
+      createCommentVariables = {
+        postId: 'p1',
+        content: '    '
+      }
+
+      await expect(client.request(createCommentMutation, createCommentVariables))
+        .rejects.toThrow('Comment must be at least 1 character long!')
+    })
+
+    it('throws an error if postId is sent as an empty string', async () => {
+      createCommentVariablesSansPostId = {
+        postId: '',
+        content: 'this comment should not be created'
+      }
+
+      await expect(client.request(createCommentMutation, createCommentVariablesSansPostId))
+        .rejects.toThrow('Comment cannot be created without a post!')
+    })
+
+    it('throws an error if postId is sent as an string of empty characters', async () => {
+      createCommentVariablesSansPostId = {
+        postId: '   ',
+        content: 'this comment should not be created'
+      }
+
+      await expect(client.request(createCommentMutation, createCommentVariablesSansPostId))
+        .rejects.toThrow('Comment cannot be created without a post!')
+    })
+
+    it('throws an error if the post does not exist in the database', async () => {
+      createCommentVariablesWithNonExistentPost = {
+        postId: 'p2',
+        content: 'comment should not be created cause the post doesn\'t exist'
+      }
+
+      await expect(client.request(createCommentMutation, createCommentVariablesWithNonExistentPost))
+        .rejects.toThrow('Comment cannot be created without a post!')
+    })
+
+    it('does not create the comment with the postId as an attribute', async () => {
+      const commentQueryVariablesByContent = {
+        content: 'I\'m authorised to comment'
+      }
+
+      await client.request(createCommentMutation, createCommentVariables)
+      const { Comment } = await client.request(commentQueryForPostId, commentQueryVariablesByContent)
+      expect(Comment).toEqual([{ postId: null }])
+    })
   })
 })