Hey there,

After reading through the manual, HAI and 12 pages of posts matching my search criteria on the subject, i decided to post. As the subject says, I have a bi-directional parent/child relationship, mapped as inverse=true and cascade="all-delete-orphan" on the parent side. When I delete a parent instance, hibernate correctly deletes all children attached to that instance. However, sql log shows that hibernate issues a separete delete statement for each child. This behaviour is also documented in the reference manual:



The part I'm not clear about is the "Of course" part of the statement. I fail to see how an "inverse" declaration would alter the semantics of "cascade", since it's been noted elsewhere by the hibernate team that "inverse" and "cascade" declarations have no relation whatsoever.

Theoretical question aside, is there any way to get one-shot delete working on a bi-directional association?

I'm not including and mapping or code since it's working as documented, let me know if you wish to see that anyway.

Thanks.

If you're using the new HQL parser, rather than the classic, then you can issue a query to delete all the children ("delete Child where parent = :parent"). This makes it a 2-shot, rather than n+1 (because you still have to delete the parent, afterwards).

The reason for the "Of course" is because the inverse="true" attribute means that the parent-to-child association is not a lifecycle-enforcing relationship. That's the whole point of it. If you want cascade="delete" to delete children a collection (as opposted to objects in a simple association), then you use inverse="false": that's what it's for.

Are you sure that you need inverse="true" on the parent-to-child collection? If you want the childrens' lifecycle to be dependent on the parent, then inverse="true" belongs on the other side of the relationship.

Hmm well, I thought "cascade" attribute is the one that defines lifecycle relationship -- Section 10.11 (Transitive persistence) of the reference manual certainly gives that impression, and makes no mention of "inverse" in the context of lifecycle enforcement.



That's exactly what I'm trying to accomplish actually, having the children's lifecycle bound to the parent. The reason I had inverse="true" on the parent side is, well, child side declaration (many-to-one in that case) does not support the inverse attribute. So if there's a way to move inverse="true" declaration to the child side, I can't seem to figure that one out.

I've managed to come up with a working binding with inverse="false" on the parent side, that however still fails to perform a one-shot delete. I've also isolated the behaviour to a simple mapping involving 2 tables and 2 classes only (Parent and Child, adapted from onetomany test-case from the distribution), I can post those if you need to see the specifics.

Thanks,

The only cascade style that makes lifecycle implications is delete-orphan. Even cascade="delete" doesn't strictly promise to delete something, it only promises to execute the delete operation on it. The delete operation might be a no-op, if the thing to be deleted has other references pointing to it. In section 10.11, the only reference to lifecycle says pretty much that:

inverse="false" is the attribute that really implies a lifecycle relationship.

I don't know why you're not getting a one-shot (properly, a two-shot) delete if you've got:

• A colleciton mapping (as opposed to a bidirectional association, perhaps a many-to-many).
• No inverse="true" attribute (adding inverse="false" makes it self-documenting)
• cascade="delete" or cascade="delete-orphan" (or any cascade that includes either of those).

If code from the distribution isn't showing the effects that it claims to, it may be that the mapping dates from an older distribution and is simply out of date. Can you modify the mapping to produce the required results? If you can, you should send the update to Christian (he's still maintaining the docs, I think).

I feel that one-shot-delete does not really work for entity relationships i.e. when both the parent and children are entities. If you always access the child via the parent, map the child with a value semantic using composite element. Children mapped with a value semantic would give the desired one-shot-delete.

Can you share your value semantic using composite element here as a sample?

See the ref docs, section 8.2, "Collections of dependent objects".