class AlterUserActivities < ActiveRecord::Migration def up UserActivity.all.each do |activity| if activity.act_type == 'Message' if activity.act unless activity.act.parent_id.nil? parent_act = UserActivity.where("act_id = #{activity.act.parent.id} and act_type='Message'").first parent_act.created_at = activity.act.parent.children.maximum("created_on") parent_act.save activity.destroy end else activity.destroy end end end end def down end end