Hi Everybody,

I'm an Hibernate newbie from now 2 weeks and I'm still confused about how to cleary design ternary associations.

Here's the asssociation I want to map :

- An ObjectA can be manipulated by several Users,
- A User can manipulated several ObjectA,
- But one User has a unique RightType for a ObjectA.

So it means (but maybe I'm wrong) that I should have into the entity table a unique composed key, composed of the foreign keys of ObjectA and User, plus a many-to-one association to RightType.

Can somebody tell me how to do this mapping ?
Better approach ?

Thanks for any help,

There are three different approaches:

* make the link an entity class
* make the link a composite-element
* make it a Map


which one would you like?

Well ... to be honest (And I apologize for this) I don't really know as I don't see what are the pros and cons of each of them.

I will say either as a entity or as a composite-element. What is exactly the difference ?

(P.S: thanks for your quick reply)

Anybody has any idea ? or am I stupid ?

Hi Philippe,

IF you are stupid, you are certainly NOT alone on this. I haven'r been able to find a clear and consice description of the differences in usage and so on for the different ternary mapping strategies.

What I learned so far (I'm a newbie) is that, for cla A, B and C:

A contains a map with B as index, it will only be possible to enter ONE C for each unique B, not a collection of C:s.

Have you seen the excellent
http://www.xylax.net/hibernate/
?
Check out "Ternary association", maybe that's a good strategy for your perticiular needs (if you haven't solved them already)

Sincerely,

/C