Clean up usages of Mongoid to generate cleaner code / queries.

api/comment_threads.rb

-get "#{APIPREFIX}/threads" do # retrieve threads by course
+require 'new_relic/agent/method_tracer'
 
-  threads = Content.where({"_type" => "CommentThread", "course_id" => params["course_id"]})
+get "#{APIPREFIX}/threads" do # retrieve threads by course
+  threads = CommentThread.where({"course_id" => params["course_id"]})
   if params[:commentable_ids]
     threads = threads.in({"commentable_id" => params[:commentable_ids].split(",")})
   end

presenters/thread_utils.rb

@@ -28,10 +28,10 @@ module ThreadUtils
           thread_key = t._id.to_s
           if read_dates.has_key? thread_key
             is_read = read_dates[thread_key] >= t.updated_at
-            unread_comment_count = Comment.collection.find(
+            unread_comment_count = Comment.where(
               :comment_thread_id => t._id,
               :author_id => {"$ne" => user.id},
-              :updated_at => {"$gte" => read_dates[thread_key]}
+              :updated_at => {"$gte" => read_dates[thread_key]},
               ).count
             read_states[thread_key] = [is_read, unread_comment_count]
           end