休眠级联 - 更新孩子为空 [英] hibernate cascade - update child to null

问题描述

我在事件和会话之间有一对多的关系。我想级联更新会话中的事件fk为空，当我删除相应的事件。任何线索如何做到这一点？
Thanks and advance。

解决方案

Hibernate或JPA不幸没有Cascade类型'SET为NULL'，但你应该可以通过@PreRemove

在一方（所有者）上做到这一点：

  @OneToMany（mappedBy =whatever）
 public List< SomeEntity> getSomeEntity（）{
返回someEntity; 
 
 
 @PreRemove 
 public void onDelete（）{
 for（SomeEntity se：getSomeEntity（））{
 se.setOwner（null）; 
} 
} 
  

希望有帮助。

I have a one to many relationship between event and session. I'd like cascade to update event fk in session to null when i delete the corresponding event. Any clue how to do this? Thanks and advance.

解决方案

Hibernate or JPA unfortunately don't have a Cascade type 'SET to NULL' but you should be able to do it with @PreRemove

on the one side (Owner):

@OneToMany(mappedBy="whatever")
public List<SomeEntity> getSomeEntity(){
    return someEntity;
}

@PreRemove
public void onDelete(){
    for(SomeEntity se : getSomeEntity()){
        se.setOwner(null);
     }
}

Hope that helps.

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