class UpdateAttachment < ActiveRecord::Migration def up count = Attachment.all.count / 30 + 2 transaction do for i in 1 ... count do i Attachment.page(i).per(30).each do |attachment| if attachment.container_type == 'Course' course = attachment.course if course if course.is_public == 0 attachment.is_public = 0 attachment.save end end end end end end end def down end end