consistency check, need to also ensure delete cleans stuff up, maybe make notifications trashable

app/models/notification.rb

@@ -13,6 +13,17 @@ class Notification < ActiveRecord::Base
   after_save :refresh_notification_count
   after_destroy :refresh_notification_count
 
+  def self.ensure_consistency!
+    Notification.exec_sql("
+    DELETE FROM Notifications n WHERE notification_type = :id AND
+    NOT EXISTS(
+      SELECT 1 FROM posts p
+      JOIN topics t ON t.id = p.topic_id
+      WHERE p.deleted_at is null AND t.deleted_at IS NULL
+        AND p.post_number = n.post_number AND t.id = n.topic_id
+    )" , id: Notification.types[:private_message])
+  end
+
   def self.types
     @types ||= Enum.new(
       :mentioned, :replied, :quoted, :edited, :liked, :private_message,

lib/jobs/ensure_db_consistency.rb

@@ -5,6 +5,7 @@ module Jobs
       TopicUser.ensure_consistency!
       UserVisit.ensure_consistency!
       Group.refresh_automatic_groups!
+      Notification.ensure_consistency!
     end
   end
 end

spec/models/notification_spec.rb

@@ -201,4 +201,27 @@ describe Notification do
     end
   end
 
+  describe 'ensure consistency' do
+    it 'deletes notifications if post is missing or deleted' do
+
+      ActiveRecord::Base.observers.disable :all
+      p = Fabricate(:post)
+      p2 = Fabricate(:post)
+
+      Notification.create!(read: false, user_id: p.user_id, topic_id: p.topic_id, post_number: p.post_number, data: '[]',
+                           notification_type: Notification.types[:private_message])
+      Notification.create!(read: false, user_id: p2.user_id, topic_id: p2.topic_id, post_number: p2.post_number, data: '[]',
+                           notification_type: Notification.types[:private_message])
+
+      Notification.create!(read: false, user_id: p2.user_id, topic_id: p2.topic_id, post_number: p2.post_number, data: '[]',
+                           notification_type: Notification.types[:liked])
+      p2.trash!
+
+      # we may want to make notification "trashable" but for now we nuke pm notifications from deleted topics/posts
+      Notification.ensure_consistency!
+
+      Notification.count.should == 2
+    end
+  end
+
 end