JPA实体两次映射到另一个类，一次删除

Question

I have a following problem, have the device:

@OneToMany(mappedBy = 'sender', cascade = CascadeType.ALL, fetch = FetchType.EAGER) Set<Gift> sentGifts = []
@OneToMany(mappedBy = 'receiver', cascade = CascadeType.ALL, fetch = FetchType.EAGER) Set<Gift> receivedGifts = []

And gift:

@ManyToOne Device sender
@ManyToOne Device receiver

Problem is that I cannot understand how to properly delete gift.

I can do > gift.sender = null > save(gift) > gift.receiver = null > save(gift) > ...

But i believe that this is not the correct way to do this, maybe cascade should be specified somehow in another way?

Thanks!

Answer 1

You should make updates to the devices referencing the gift before removing it, as otherwise those references will still exist in your object model and might cause the gift to be resurrected. Removing the gift from the senders set of sentGifts and the receivers set of receivedGifts, then save both, then remove the gift should be enough. The changes to the sender and receiver device won't result in database changes; they are only to keep your entities inline with what you want in the database, but should be done as entities can be cached in JPA. There is no reason to null out receiver or sender on the gift before deleting the gift.