@@ -1,4 +1,7 @@
 class SubscribeOldChangesets < ActiveRecord::Migration[4.2]
+  class Changeset < ActiveRecord::Base
+  end
+
   def up
     Changeset.find_each do |changeset|
       changeset.subscribers << changeset.user unless changeset.subscribers.exists?(changeset.user.id)
class SubscribeOldChangesets < ActiveRecord::Migration[4.2]
  def up
    Changeset.find_each do |changeset|
      changeset.subscribers << changeset.user unless changeset.subscribers.exists?(changeset.user.id)
    end
  end

  def down; end
end

I think this will fail if there are changesets in the database as the migration relies on the `subscribers` and `user` associations on the changeset.