change semester_feedback relation from polymorph to or relation

app/models/assignment.rb

@@ -2,11 +2,15 @@ class Assignment < ApplicationRecord
   include AssignmentCommon
   include VolunteersGroupAndTandemStateUpdate
 
+  has_one :assignment_log
+
   has_many :hours, as: :hourable
   has_many :feedbacks, as: :feedbackable
   has_many :trial_feedbacks, as: :trial_feedbackable
-  has_many :semester_feedbacks, as: :semester_feedbackable
-  has_one :assignment_log
+
+  # Semester process relations
+  #
+  has_many :semester_feedbacks, dependent: :destroy
 
   validates :client_id, uniqueness: {
     scope: :volunteer_id, message: I18n.t('assignment_exists')

app/models/concerns/group_assignment_common.rb

@@ -8,7 +8,7 @@ module GroupAssignmentCommon
     belongs_to :group_offer, -> { with_deleted } # include imported deleted group offers
     has_many :reminder_mailing_volunteers, as: :reminder_mailable, dependent: :destroy
 
-    has_many :semester_feedbacks, as: :semester_feedbackable
+    has_many :semester_feedbacks, dependent: :destroy
     has_one :group_offer_category, through: :group_offer
     has_one :creator, -> { with_deleted }, through: :group_offer
 

app/models/semester_feedback.rb

@@ -5,5 +5,18 @@ class SemesterFeedback < ApplicationRecord
   has_one :volunteer, through: :semester_process_volunteer
 
   # relates to either Assignment or GroupAssignment (not GroupOffer!)
-  belongs_to :semester_feedbackable, polymorphic: true, optional: true
+  belongs_to :assignment, optional: true
+  belongs_to :group_assignment, optional: true
+
+  validate :validate_group_assignment_or_assignment_present
+
+  def mission
+    group_assignment || assignment
+  end
+
+  private
+
+  def validate_group_assignment_or_assignment_present
+    errors.add(:association_insuficient) if assignment.blank? && group_assignment.blank?
+  end
 end

db/migrate/20181004141844_create_semester_feedbacks.rb

@@ -4,8 +4,9 @@ class CreateSemesterFeedbacks < ActiveRecord::Migration[5.1]
       t.references :author, references: :users, index: true
       t.references :semester_process_volunteer, index: false
       # for relations to either Assignment or GroupAssignment (not GroupOffer!)
-      t.integer :semester_feedbackable_id
-      t.string :semester_feedbackable_type
+      t.references :assignment, foreign_key: true
+      t.references :group_assignment, foreign_key: true
+
       t.text :goals
       t.text :achievements
       t.text :future

test/factories/semester_feedbacks.rb

 FactoryBot.define do
   factory :semester_feedback do
     association :author, factory: :user
-    volunteer
     semester_process_volunteer
+    volunteer
     goals 'Goals text'
     achievements 'Achievements text'
     future 'Future text'
     comments 'Comments text'
-    association :semester_feedbackable, factory: :group_assignment
+
+    after(:build) do |sem_fb|
+      if sem_fb.assignment.blank?
+        sem_fb.group_assignment ||= FactoryBot.build(:group_assignment)
+      end
+    end
   end
 end

test/factories/semester_process_volunteers.rb

 FactoryBot.define do
   factory :semester_process_volunteer do
     volunteer
-    semester_process
-
+    semester_process_volunteer_missions
+    hours
+    semester_feedbacks
     notes { ['some note', 'another note'] }
   end
 end