I'm just starting out, testing Hibernate, and attempting to model a parent/child relationship onto a legacy database.

My schema looks like this:

In the child table, the key is (parentid, childid). Note that childid is not unique across the table; it numbers 1...n for each instance of parent.

I'm not sure how to model this properly for a one-to-many inverse relationship. I've gotten a simple parent->child set to work, but not a relationship where the child can access its parent.

Any samples out there? I understand that surrogate keys would be best, but adding them is not an option right now.

Thanks,
Steve

You should since your child refers parent_id, and thus parent.

The one-to-many is mapped as a plain old one-to-many, no particularity

Thanks. But the parent -> child relationship was not the problem. It was the reciprocal relationship--the child accessing the parent.

The composite-id of (parentid, childid) didn't seem to get along with the <many-to-one> mapping from the child.

I got around this by modifying the child hbm.xml mapping so it doesn't consider the parent id part of its key. (No composite id block, just one <id> of childid.) The parent id is only mentioned in a <many-to-one> element. However, now the parentid field in the child is not initialized at all.

Perhaps I should forgo having both a parent reference and a parentid field in my child class...? If I want the parent's id I can always call child.getParent().getId()....

Steve

use <key-many-to-one> Have a look at the dtd

Now that you said it, I see it there in the reference, under <composite-id>. Missed it before. Thanks.

Steve