updated rails to 4.2.4

app/controllers/admin/comments_controller.rb

@@ -0,0 +1,30 @@
+module Admin
+  class CommentsController < Admin::BaseController
+    load_and_authorize_resource :conference, find_by: :short_title
+    load_and_authorize_resource
+
+
+    def index
+      # All available comments, grouped and sorted
+      @comments = grouped_comments(accessible_ordered_comments)
+
+      # Grouped, sorted, available comments, posted since current_user last login
+      @unread_comments = grouped_comments(accessible_ordered_comments.find_since_last_login(current_user))
+
+      # Grouped, sorted, available comments, posted by current_user
+      @posted_comments = grouped_comments(accessible_ordered_comments.find_comments_by_user(current_user))
+    end
+
+    private
+
+    # Returning all available comments, ordered by created_at: :desc and by event.title
+    def accessible_ordered_comments
+      Comment.accessible_by(current_ability).joins('INNER JOIN events ON commentable_id = events.id').order('events.title', 'comments.created_at DESC')
+    end
+
+# Grouping all comments by conference, and by event. It returns {:conference => {:event => [{comment_2}, {comment_1 }]}}
+    def grouped_comments(remarks)
+      remarks.group_by{ |comment| comment.commentable.conference }.map {|conference, comments| [conference, comments.group_by{|comment| comment.commentable}]}.to_h
+    end
+  end
+end