@EmbeddableSuperclass, @IdClass and @ManyToOne

g.tomassoni · **Posted:** Thu Jan 12, 2006 2:05 pm

Hibernate version: 3.1
Hibernate-annotations version: 3.1beta7
Mapping documents: EJB+Hibernate annotations

Dears,

don't know if it is because I'm not supposed to do it, but the following stuff:

Code:

@EmbeddableSuperclass(access = AccessType.FIELD)
public class A_PK implements Serializable {
    @ManyToOne
    @JoinColumn(name = "idB")
    @NotNull
    public B b;

    @ManyToOne
    @JoinColumn(name = "idC")
    @NotNull
    public C c;

    ...

}


@Entity(access = AccessType.FIELD)
@Table(name = "A")
@IdClass(A_PK.class)
public class A extends A_PK {
    @Column(length = 16)
    @NotNull
    public String someText;

    ...
}


@Entity(access = AccessType.FIELD)
@Table(name = "B")
public class B {
    @Id
    public Integer id;

    @OneToMany(mappedBy = "b")
    public Collection<A> as;

    ...
}


@Entity(access = AccessType.FIELD)
@Table(name = "C")
public class C {
    @Id
    public Integer id;

    @OneToMany(mappedBy = "c")
    public Collection<A> as;

    ...
}

causes an:

Quote:

org.hibernate.MappingException: property not found: c on entity A

This happens during the Collection Mapping phase (processing collection mappings). More precisely, during the:

Quote:

Mapping collection: C.as -> A

I didn't find anything like this in the test cases of my hibernate-annotations.jar and both the ejb-3.0 and hibernate-annotations specs are a bit scarce of hints about how to mimic the old <key-many-to-one> construct with annotations. Also, the kind of error seems to be related to a problem with the @EmbeddableSuperclass thing.

Am I wrong (once more), or the above-shown class setup is supposed to work with hibernate-annotations, maybe sometime in the future?

Regards,

PS: I have a testcase file for this, in case this is an hibernate-
annotations issue instead then a Giampaolo's one...
PPSS: I posted this also on the Hibernate Users forum, but probably this
one is closer to the matter. Sorry for the crosspost.

emmanuel · **Posted:** Thu Jan 12, 2006 4:01 pm

@ManyToOne is not yet supported on component nor component ids

having a superclass also the PK is really weird, I haven't tested such case

g.tomassoni · **Posted:** Thu Jan 12, 2006 4:12 pm

Well, it worked with hbm. And, after all, I don't think it's so weird:

1) you have to bring the very same persisted attributes of the PK into the entity anyway;

2) the Serializeable interface is already implemented in the PK and it makes sense to me to carry it in the entity, too;

3) PK attributes are just, well, entity attributes this way, a feature that @EmbeddedId wouldn't satisfy;

4) this design seems clever to me than having an entity and its pk related only by an attribute.

Does it break any pattern or design?

emmanuel · **Posted:** Fri Jan 13, 2006 5:41 am

I'll need to test, but there is no reason why it should break HA.
I still conceptually prefer @EmbeddedId since the entity is not its own PK.

g.tomassoni · **Posted:** Fri Jan 13, 2006 8:05 am

I can spare you a testcase by e-mail, if you like.

Thanks,

emmanuel · **Posted:** Fri Jan 13, 2006 10:32 am

post a runnable version to JIRA but wo the @ManyToOne
Thanks

g.tomassoni · **Posted:** Fri Jan 20, 2006 10:29 am

Sorry for this late reply to you, Emmanuel. Somehow, I didn't get an e-mail notice about your message.

I prepared a testcase without the @ManyToOne in the PK class as required, but that way I found jboss to smoothly deploy it.

This probably mean that the problem is somehow related to the @ManyToOne-in-the-pk case, not to the @IdClass thingery.

Do I have to drop a copy of this testcase to JIRA anyway?

Regards,