class MigrateWebPushSubscriptions2 < ActiveRecord::Migration[5.2] disable_ddl_transaction! def up Web::PushSubscription.where(user_id: nil).select(:id).includes(:session_activation).find_each do |subscription| if subscription.session_activation.nil? subscription.delete else subscription.update_attribute(:user_id, subscription.session_activation.user_id) end end end def down # Nothing to do end end