I am having a problem removing elements from a collection and having the updated collection persisted correctly when using a OneToMany mapping.

Here's the mapping as specified in the 'parent' class:


What I'm finding is that when I remove Member instances from the collection held ParentImpl, when I persist ParentImpl, the references removed from that collection are not removed from the MemberImpl table. When I reload the ParentImpl call members I removed from the collection, are repopulate from the MemberImpl table.

I understand that, since I'm not removing the parent instance, then it might follow that the cascade doesn't have to propagate the removal of the related member instances however, if I UPDATE the collection with more members, and persist ParentImpl, then a cascade does occur, as the new members appear in the MemberImpl.

So, it appears that for create/update operations, cascading works perfectly, however for delete operations ,it only appears to propagate if the parent instance is deleted.
This strikes me as wrong - how can I set up EJB3 to allow me to remove entries from the collection, and have those entries removed from the related table without removing the parent instance.

As a comparison, I tried the same operation using the Hibernate Core implementation using the following mapping:



This behaves correctly, when I removed members from the collection, these removals were correctly unpersisted in the 'member' table.

So, my question then, is how do I configure EJB3 EntityManager annotations to succesfully propagate removals from a collection, when the parent instance holding the collection is not being deleted.

This is especially frustrating when the Hibernate core implementation appears to support this perfectly.

@org.hibernate.annotations.CascadeType(DELETE_ORPHAN)

Hello Emmanuel,

DELETE_ORPHAN?

How would I use this with my EJB annotation, when I tried to do cascade=CascadeType.DELETE_ORPHAN, I get an error.

Forgive me if I'm doing something wrong here - I've very new to EJB3 persistence - can you advise me how I'd use this cascade type?

-Thom

instead of

@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="relatedMember", targetEntity=MemberImpl.class)
public Collection<Member> getMembers() { return members;}
…
}


Try

@OneToMany(fetch=FetchType.LAZY, mappedBy="relatedMember", targetEntity=MemberImpl.class) @org.hibernate.annotations.Cascade({org.hibernate.annotations.CascadeType.ALL,
org.hibernate.annotations.CascadeType.DELETE_ORPHAN})
public Collection<Member> getMembers() { return members;}
…
}


Ethan

wow.

Thanks, clearly I have much to learn!

Though it strikes me that the EJB cascade defaults need some work for, without the Hibernate extensions, I;d be out of luck!

Thanks again

-Thom

After mulling this fix - it occurs to me that there is a short-coming with the default implementation of cascade deletes with the EJB 3 EntityManager implementation.

The above scenario demonstrates that there is a gap in what the EJB3's implementation of cascading delete operations can cover.

Do you think it is valid to raise this as a shortcoming with EJB3 on the relevent sun forum? (b.t.w. - if anyone knows the appropriate forum to raise this issue, please do tell!)

-Thom