Mapping advice needed: different collections to same table

rwwilden · **Joined:** Tue May 31, 2005 8:57 am **Posts:** 10

Hibernate version: 3.0.5

Hi,

I'd like some help mapping a particular class and it's relations. The class is supposed to look like this:

Code:

public class Term {
   private Set<Term> someTerms;
   private Set<Term> someOtherTerms;
   private Set<Term> someMoreTerms;
}

The Term class is mapped to the TERM table and the collections should also be mapped to the TERM table. But they should also be split into separate collections. Can this be accomplished? I could not find any information on this.

Regards,
Ronald Wildenberg.

TheXFed · **Posted:** Tue May 31, 2005 1:55 pm

Yes, I've been able to do what you're talking about. Look in the guide for "discriminators". Basically you need a column in the table to differentiate which collection a row in the table will belong to.

In the case which I'm working with, each collection is mapped to a different class, each defining their discriminator value. Each of these classes extend from a superclass that defines all of the common fields in that table, as well as the column name and type of the discriminator column.

We use XDoclet, so here's an example of class-level tags for defining them:

<Superclass>
@hibernate.discriminator
column="type"
type="string"

<Subclass1>
@hibernate.subclass
discriminator-value="A"

<Subclass2>
@hibernate.subclass
discriminator-value="B"

<Subclass3>
@hibernate.subclass
discriminator-value="C"

When you map the collections, just map one collection to Subclass1, one to Subclass2, and one to Subclass3. They will all map to the same table, and the discriminator is taken care of automatically.