In my understanding,

In case of a one to many bidirectional association, with inverse set to true and foreign key set to NOT NULL. If saving the parent is to be cascaded to its children then all is needed is setting the parent pointer in child, adding child to parent and then inserting parent. Inserting parent will then be cascaded to its children which will also be inserted. Thats well and good for a bidirectional association.

My problem is with the case of a one to many association that is not bidirectional, with inverse set to false and foreign key set to NOT NULL, and saving the parent is to be cascaded to its children. Now when I add child to parent and then insert parent Hibernate throws the SQLException that


When at the application level the child has been added to parent then why doesnt Hibernate insert the foreign key while inserting child record. I guess the pattern Hibernate follows is: Insert Child record and then update Child record with the foreign key. Why cant all this be done in one single Child record insert in which the foreign key is also inserted

Is there a way around this problem?
Thanx in advance for suggestions and tips

You may not use a unidirectional association for a column with a NOT NULL constraint.

Thanx a alot!

I see that if I allow NULL for FK and set inverse to false then Hibernate appropriately inserts : Insert Parent, Insert Child and then update Child with FK

but if I set inverse to true then Hibernate insert Parent, inserts Child but doesnt update Child with FK

Thanx once again for ur advice!

Gavin, why is this so? Is this a Hibernate thing or is there a principle here that I am not familiar with? I think that this statement is pretty important: I didn't see it in the documentation.

It is actually written in the doco in a couple of places.

The reason it is like this is that Hibernate

(a) prefers generation of SQL strings at config time
(b) supports detached objects

we consider both of these things as more important than supporting not-null unidirectional associations.

And its pretty much a case of "we can't have all three".


(There are *some* things we could do to try and improve it a bit but they are ugly.)