Hello,

Hibernate seems to work fine when you are following standard inheritance hierarchies, but I'm unable to get it working with delegation/composition style design.

I have interfaces A, B and B extends interface A:

A {

doA();

getID();

}

B extends A {

doB();

}

I then have AImpl and BImpl, but BImpl does not extend AImpl. BImpl instead uses composition/delegation and contains a field of type A.

So:

BImpl implements B {

A myA;

doA() {
myA.doA();
}

doB() {
1 + 1;
}

getID() {
myA.getID();
}

}


Now, the ID is in A, and when I write the mapper for BImpl I need to write a component element of A and have the ID property pulled from that. Hibernate doesn't seem to work here. If I declare the component of class="A" it gives a reflection error at runtime. If I declare the component of class="AImpl", first this is breaking the whole interface dependency, and second I get an error that the id property is not found.

So, how can I map the BImpl situation above? Is this a bug in hibernate?

Thanks

How would this be a bug, exactly?

Your domain model is sort of schizophrenic. At the interface level you describe it using an inheritence model, at the class level you instead try to say the association is rather a composition. So which is it?

Totally inferring from what I think you are trying to do, I would say that you really want a one-to-one relationship between A and B (they share the same key right?). Then if you want an interface over top of that which conceptually runs counter to the actual implementation, then just do it. When mapping things in hibernate, the way you conceptualize the associations at the class level is the way to map it.

It seems that if I have the component mapping that says the key is in the B type, Hibernate should be able to successfully pull it out when it deals with an A type.

Is it safe to say that all concrete persistent classes must be known by Hibernate? I'm having a lot of trouble trying to program only to interfaces, but still use Hibernate.