I have a table we can call Parent_Child in a legacy system. This table connects parents and children. The primary key is ParentId and ChildId as a composite-id.

However, both parent and child are really the same object, Person. So I have a many-to-one relationship to Person for both these columns, i.e., two relationships to the same table.

I also have a relationship to another table, so I cannot change the table structure here, but am forced to live with it.

My question is: How do I connect Parent_Child to Person in the hbm.xml files? I can do something like this in ParentChild.hbm.xml:

<many-to-one
name="parent"
class="Person"
column="PARENTID"
insert="false"
update="false"
/>

<many-to-one
name="child"
class="Person"
column="CHILDID"
insert="false"
update="false"
/>

But how do I map this relationship in Person.hbm.xml?

I can do this:

<set
name="parentchildren"
inverse="true"
>
<key
column="PERSONID" />
<one-to-many
class="ParentChild"
/>
</set>

That's one column. How do I map the other one? What do I call the set? Or am I going about this the wrong way? :)

I'd really appreciate any input on this. Thanks.

Kristoffer

Edit: After looking through the manual once again I stumbled onto paragraph 8.4. Could this be what I want? But on the other hand it seems to be based on the fact that Person has a composite primary key, which it has not ...

This is a many-to-many with join table. See section 7.5.3. "many to many", of the ref docs. Just swap "Child" in for "Address" :)

Hm, I don't think so ... In 7.5.3 you have three tables, in this case it would be Parent, Child and ParentChild. However, I only have two tables, Person and ParentChild. ParentChild is sort of a join table between two Persons.

Or am I misunderstanding you? :)

I think I solved it.

I now do this in "PersonChild.hbm.xml":

<many-to-one
name="parent"
class="Person"
column="PARENTID"
insert="false"
update="false"
/>

<many-to-one
name="child"
class="Person"
column="CHILDID"
unique="true"
insert="false"
update="false"
/>

Turns out what I really want is a one-to-one relationship between the childId and Person, but a many-to-one relationship between the parentId and Person.

This is how it looks in "Person.hbm.xml" now:


<one-to-one
name="child"
class="PersonChild"
property-ref="child"
/>

<set
name="parents"
inverse="true"
>

<key
column="PARENTID" />
<one-to-many
class="ParentChild"
/>
</set>

Kristoffer