Hey, I'm trying to map a one-to-one relationship from a table I'm creating to a table that currently exists; the default behavior for a one-to-one relationship is just to have the two entities have the same id value; this is not an option for me. I want to create a one-to-one relationship in which hibernate maps the relation with an additional column in the table.

For example:
I want a one-to-one relation of students to lockers;

so I have student(id, name) and locker (id, number). The default behavior is for the student and locker to have the same id value; what I need to do is: student(id, name, lockerid) and locker(id, number) where lockerid is the id of the locker entry. I can't seem to make the one-to-one mapping behave like this.

There is a bit at the end of section 5.1.11 in the hibernate documentation about this (http://www.hibernate.org/hib_docs/v3/reference/en/html_single/#mapping-declaration-onetoone).

It is a little bit unintuitive but you need to use a many-to-one association with the unique setting set to true instead of one-to-one.

So for your particular case I would expect the mapping for the Student class to contain something like:



If the association is bi-directional then I would also expect the mapping for the Locker class to contain something like:



Cheers