[deploy] Remove orphaned DisplayAdEvent rows (#9765)

* Remove orphaned DisplayAdEvent rows

* Add dependent in the has_many relationship between ads and ad events

app/models/display_ad.rb

@@ -1,6 +1,6 @@
 class DisplayAd < ApplicationRecord
   belongs_to :organization
-  has_many :display_ad_events
+  has_many :display_ad_events, dependent: :destroy
 
   validates :organization_id, presence: true
   validates :placement_area, presence: true,

lib/data_update_scripts/20200813072205_remove_orphaned_display_ad_events.rb

@@ -0,0 +1,21 @@
+module DataUpdateScripts
+  class RemoveOrphanedDisplayAdEvents
+    def run
+      # Delete all DisplayAdEvents belonging to DisplayAds that don't exist anymore
+      ActiveRecord::Base.connection.execute(
+        <<~SQL,
+          DELETE FROM display_ad_events
+          WHERE display_ad_id NOT IN (SELECT id FROM display_ads);
+        SQL
+      )
+
+      # Delete all DisplayAdEvents belonging to Users that don't exist anymore
+      ActiveRecord::Base.connection.execute(
+        <<~SQL,
+          DELETE FROM display_ad_events
+          WHERE user_id NOT IN (SELECT id FROM users);
+        SQL
+      )
+    end
+  end
+end

spec/models/display_ad_spec.rb

@@ -4,11 +4,18 @@ RSpec.describe DisplayAd, type: :model do
   let(:organization) { create(:organization) }
   let(:display_ad) { create(:display_ad, organization_id: organization.id) }
 
-  it { is_expected.to validate_presence_of(:organization_id) }
-  it { is_expected.to validate_presence_of(:placement_area) }
-  it { is_expected.to validate_presence_of(:body_markdown) }
-
   describe "validations" do
+    describe "builtin validations" do
+      subject { display_ad }
+
+      it { is_expected.to belong_to(:organization) }
+      it { is_expected.to have_many(:display_ad_events).dependent(:destroy) }
+
+      it { is_expected.to validate_presence_of(:organization_id) }
+      it { is_expected.to validate_presence_of(:placement_area) }
+      it { is_expected.to validate_presence_of(:body_markdown) }
+    end
+
     it "allows sidebar_right" do
       display_ad.placement_area = "sidebar_right"
       expect(display_ad).to be_valid