Hello everybody!
I need your assistance in some basic hibernate concepts.

I made a n:m relation via composite element.

I now fetch element 'a', and add programmatically childentities b afterwards.

After some manipulation I update 'a'. Now 'a' gets updated and all b's are saved too.

Now I exchange all compositeelements (a.b = bCollection) and update again.

After this update i have the bCollection prior to the update and the new bCollection persisted in the database.

- so far I can imagine why hibernate does that, BUT now i update 'a' again after exchanging b (a.b = newBCollection). This time the newBCollection is persisted without old ones saved.

Any ideas?

Thx in advance!

Hi marks,

Just to clarify, the code (a.b = bCollection) ... does that replace the collection property?

If so, NHibernate would not work properly if you replace its PersistentCollection objects with your own.

Regards,
Richard

Hi!

Yes, a.b = bCollection replaces the collection a.b.

What i don't understand is that it works proberly after saving it the second time.

I would fully understand that it doens't work, but somehow it does work.

Unfortunately I cannot do something like:



b/c i can't save compositeelements

Hi,

If 'a' is a persistent entity, then I don't think you can write: a.b = new Collection()

This replaces NHibernate's PersistentCollection, and all bets are off as to the behaviour after that.

I think your only options are to either:

1. Delete all the existing entries in the collection, followed by re-adding the new ones;

2. Figure out the added/deleted ones, and update the a.b collection to match your other collection.

Hope that helps.

Regards,
Richard

how do i delete composite elements?
i could only :

I think the original code you had would work to delete, so to delete and re-add, I was imagining something like (based on your original snippet):



or if you specify "all-delete-orphan" in your one-to-many collection, something like:



Regards,
Richard

yes, but unfortunately I can't delete Compositeelements. Hibernate complains that there is no mapping specified

Hi,

Can you post the mapping, code, and exception you're getting?

Cheers,
Richard

its a usual <bag><comp-ele></comp-ele></bag> mapping.
exception tells me that there is no mapping file for b.

Is there no better / cleaner way to remove composite elements, than a.b = null; dao.save(a) ?

btw: i cant do a dao.save(b) b/c b is a composite element!

It will work in the usual way then. :-)





should work OK.