Make handle_threads_query scope all queries by course_id so that everything that uses it is scoped.

api/comment_threads.rb

@@ -30,7 +30,7 @@ post "#{APIPREFIX}/threads/:thread_id/comments" do |thread_id|
   comment = Comment.new(params.slice(*%w[body course_id]))
   comment.anonymous = bool_anonymous || false
   comment.anonymous_to_peers = bool_anonymous_to_peers || false
-  comment.author = user 
+  comment.author = user
   comment.comment_thread = thread
   comment.save
   if comment.errors.any?

api/notifications_and_subscriptions.rb

@@ -3,7 +3,7 @@ get "#{APIPREFIX}/users/:user_id/notifications" do |user_id|
 end
 
 get "#{APIPREFIX}/users/:user_id/subscribed_threads" do |user_id|
-  handle_threads_query(user.subscribed_threads.where(:course_id=>params[:course_id]))
+  handle_threads_query(user.subscribed_threads)
 end
 
 post "#{APIPREFIX}/users/:user_id/subscriptions" do |user_id|

lib/helpers.rb

@@ -76,7 +76,7 @@ helpers do
   end
 
   def handle_threads_query(comment_threads)
-
+    comment_threads = comment_threads.where(:course_id=>params[:course_id])
     if CommentService.config[:cache_enabled]
       query_params = params.slice(*%w[course_id commentable_id sort_key sort_order page per_page user_id])
       memcached_key = "threads_query_#{query_params.hash}"
@@ -105,6 +105,7 @@ helpers do
     sort_key = sort_key_mapper[params["sort_key"]]
     sort_order = sort_order_mapper[params["sort_order"]]
     sort_keyword_valid = (!params["sort_key"] && !params["sort_order"] || sort_key && sort_order)
+
     if not sort_keyword_valid
       {}.to_json
     else