Howto only delete un-referenced entities with cascade?

Linuxhippy · **Joined:** Tue Jul 03, 2007 8:47 am **Posts:** 46

Hello,

I have two Classes which have a ManytoMany relationship with each other:

Code:

public class Peer implements Serializable{
........
    @ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE })
    private Set<SharedFile> files = new HashSet<SharedFile>();
}

public class SharedFile implements Serializable {
.............    
    @ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE })
    private Set<Peer> peers = new HashSet<Peer>();

So a Peer can have many shared files, and a shared file can have many peers.
However when I delete a single peer (using session.delete(peer)), ALL referenced SharedFiles are also deleted, even if they are still referenced by other Peers. Deleting the SharedFile cascades to their peers and in the end I have an empty database.

Is there any way to only cascade-delete SharedFile, if no other peer does reference it?
If I remove the CascadeType.Remove from SharedFile (to not delete other Peers which share the same file), I get an exception:

Code:

SCHWERWIEGEND: Integrity constraint violation FK286ACA391E1BF993 table: PEER_FILE in statement [delete from FILE where file_id=?]
04.11.2008 22:56:12 org.hibernate.event.def.AbstractFlushingEventListener performExecutions
SCHWERWIEGEND: Could not synchronize database state with session

Thank you in advance, Clemens

gonzao_diaz · **Joined:** Mon Nov 26, 2007 2:29 pm **Posts:** 443

Which side is the inverse?