Hello everybody!

Consider the following situation:

Entity A has a collection of Entity B. But entity A actually doesn't know about that, b/c this relation is just defined in Entity B as a <many-to-one> relation.

But whenever I delete Entity A, I want to cascade the delete command!

How can this be achieved?

My first (and ugly) approach is to define a private field in Entity A:



which, of course, results in a warning that bs is never assigned.

and then define a property in the A.hbm.xml:



How would you solve this problem??

Thx in advance & kind regards
Marks

Hi Marks,

I would do exactly what you have done ... but if you also make the field protected (instead of private) I think your compiler warning will disappear.

Regards,
Richard

When you want to use hibernate for deleting the A's, the easiest and cleanest way is the one you already tried. Alternatives may be implementing ILifecycle on A, using an interceptor in the session or define a cascading delete on the foreign key (if you have one) in the database.

If you have your own data access layer between hibernate and your application, you can do the cascade there, depends on architecture of your app.

actually there are plenty of layers :)

I also thought about a DeleteA() Method, but as I use a generic Dao that already has Delete(object _obj) I wanted to use this method in the first place.
Anyway, I also like the idea of ILifecycle a lot!

Shouldn't cascade="all" result in deleting all B's ?
Right now the whole thing seems only to work with all-delete-orphan, which kinda conflicts with my transaction management.

Hi Marks,

cascade="all" will not delete entity objects in a collection. I believe cascade="all-delete-orphan" is correct in this example. You might also want to add inverse="true" to your set, since the child object has a parent reference.

http://www.hibernate.org/hib_docs/reference/en/html/example-parentchild.html

Regards,
Richard

Just note, that ILifecycle seems to be obsolete. But I don't know if (and when) it will be removed from hibernate. Besides, if you implement OnDelete on A, then A does know something about B. Not as obviuos as with a private mapping, but from a design point it makes no difference at all.