Hi all,

I'm just wondering if it is possible to define a combined mapping for tables that are in a one-to-many relationship.

What I mean is that I am having let's say a Product table and a ProductDescription table. A Product can have many descriptions and is identified by a productId. A productDescription is having a composite-id (id, country, language).

What I would normally do is define a one-to-many from Product to ProductDescription and a many-to-one as the inverse.

But now I'm wondering if I could combine these to objects in one. I was thinking about something like mapping the productDescription and define a join to the product to include all the product attribute as well. This would keep the object models a lot simpler since I'm having a lot of such relations.

It seems, however, that this ain't working since "the foreign key must have the same number of columns as the primary key".

Also... if it would be possible to define such a mapping.... would it be writable? Since the product table is the base table the entries have to be inserted there before one could insert something into the description table.

Hopeing somebody could give me a quick "Yes... it's possible" or "No.. can't do..."... Longer answer will be appreciated as well ;-)

Thanks a lot!
TJ

It's not possible with your current configuration. And subclasses can't have different numbers of columns in the key. You could set up mappings for each country/langugage combination, but that is probably not what you want.

The one-to-many/many-to-one approach is probably correct.

Check out the <join> element, as it does something like what you want, but it is still restricted to identical primary key shapes.

If there's a single ProductDescription class and lots of other classes refer to it, you could set up a CompositeUserType for it. Combine that with a <typedef> to a short description, and you can reduce your mappings to something simple like

This solution can't work with bidirectional mappings, unfortunately.

hmm... I was afraid that it wouldn't be possible.

Would have made my object model a bit easier since no one would have had to deal with the difference of core information and description.

Anyway... since it's not possible I just stick with the one-to-many / many-to one approach...

Thanks alot for verifying my doubts!
TJ