Add filters to index page

app/models/user_exercise_feedback.rb

@@ -2,10 +2,11 @@ class UserExerciseFeedback < ActiveRecord::Base
   include Creation
 
   belongs_to :exercise
+  has_one :execution_environment, through: :exercise
 
   validates :user_id, uniqueness: { scope: [:exercise_id, :user_type] }
 
   def to_s
     "User Exercise Feedback"
   end
-end
+end