hibernate cascade - update child to null

问题

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.

回答1:

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.

来源：https://stackoverflow.com/questions/4802863/hibernate-cascade-update-child-to-null