Hi! I have a problem mapping a composite foreign key within a composite primary key. That's pretty complicated and probably bad db design but I'm not the owner of the database and I won't be able to change anything at all.

Here is an example of my problem:







Now I get the following MappingException:



When using the @AttributeOverrides annotation I can only specify one referencing column name like "firstname" (instead of both, "firstname" and "lastname":



Therefore I get the following exception (which of course is correct):




Of course, nobody would use "firstname" and "lastname" as primary key, but it's just an example of my problem.

I think it would be easier to help if we knew the DB schema you need to map; right the information provided, we don't know whether the problem is in what Hibernate provides or in the way you use it.

We have a setup with three tables in a master-detail-subdetail hierarchy, each level down the hierarchy adds another PK field.
We're not trying to model that using nested Id classes; MasterId, DetailId, and SubdetailId are just standard Id classes.
The foreign keys are set up separately.

We end up with a somewhat redundant POJO structure in the Detail classes: it has the PK values once in the id member (in the form of a DetailId object), and once in the form of a link to the Master object which in turn repeats most of the values in its own MasterId object.
These need to be set up consistently when creating new objects. Fortunately, you can't change PKs in a Hibernate-managed entity (Hibernate will throw up all over the place if you do that), so you don't need to worry about keeping that consistent for all updates. (Personally, I tend to set up an entity factory per entity class to keep such things under control.)
Note that this problem is very similar to having to set up the mutual linkage between master and detail POJOs.