Return if comment can be edited by the current user

app/controllers/comments_controller.rb

@@ -21,6 +21,7 @@ class CommentsController < ApplicationController
         comment.username = comment.user.displayname
         comment.date = comment.created_at.strftime('%d.%m.%Y %k:%M')
         comment.updated = (comment.created_at != comment.updated_at)
+        comment.editable = comment.user == current_user
       }
     else
       @comments = []

app/models/comment.rb

@@ -1,7 +1,7 @@
 class Comment < ActiveRecord::Base
   # inherit the creation module: encapsulates that this is a polymorphic user, offers some aliases and makes sure that all necessary attributes are set.
   include Creation
-  attr_accessor :username, :date, :updated
+  attr_accessor :username, :date, :updated, :editable
 
   belongs_to :file, class_name: 'CodeOcean::File'
   belongs_to :user, polymorphic: true

app/views/comments/index.json.jbuilder

@@ -1,4 +1,4 @@
 json.array!(@comments) do |comment|
-  json.extract! comment, :id, :user_id, :file_id, :row, :column, :text, :username, :date, :updated
+  json.extract! comment, :id, :user_id, :file_id, :row, :column, :text, :username, :date, :updated, :editable
   json.url comment_url(comment, format: :json)
 end