class Feedback < ActiveRecord::Base belongs_to :feedback_receiving, polymorphic: true validates :rating, presence: true, inclusion: {in: [2, 3, 4, 5, 6]} before_create :destroy_older_feedbacks_by_the_session private def destroy_older_feedbacks_by_the_session feedback_receiving.feedbacks.where(session_id: session_id).destroy_all end end