fixed response in order to redirect correctly on ajax requests. Fixed policy

app/models/user_exercise_feedback.rb

@@ -1,6 +1,6 @@
 class UserExerciseFeedback < ActiveRecord::Base
+  include Creation
 
-  belongs_to :user, polymorphic: true
   belongs_to :exercise
 
   validates :user_id, uniqueness: { scope: [:exercise_id, :user_type] }