hibernate - Grails:级联删除和外键

Question

public class Room {
  static belongsTo = [hotel:Hotel]
  Source source
  long sourceid
  RoomType type
  float price
  float oldPrice
  Currency currency
  boolean isShown = false
  boolean approved = false
  static hasMany = [roomTexts:RoomText]

  def beforeDelete () {
    Photos.withNewSession {
      Photos.findAllByRoom(this).each {photosInstance->
        photosInstance.delete()
      }
    }

    RoomFeatures.withNewSession {
      RoomFeatures.findAllByRoom(this).each {roomF->
        roomF.delete()
      }
    }
  }

}

然后:

def room = Room.get(1) 
room.delete()

将抛出com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException。

Cannot delete or update a parent row: a foreign key constraint fails (`prod_test`.`photos`, CONSTRAINT `FKC50C8881EC5F6358` FOREIGN KEY (`room_id`) REFERENCES `room` (`id`))

发生这种情况是因为照片删除 session 尚未刷新到数据库，并且Hibernate尝试删除Room实体，我认为...

这是房间删除代码:

Room.withTransaction{status->
   roomInstance.delete(flush: true)
}

是否有任何解决方法或“正确方法”来解决此问题？
当然，我可以在删除房间之前手动删除所有照片，但是使用beforeDelete有助于保持代码干净并避免代码重复。

Answer 1

为什么不能将hasMany列表中的照片与RoomText一起保存，而使照片属于Room？