Can I choose the discriminator column from another table, for instance:

]<class name="Document" table="DOCUMENTS">
<id name="id">...</id>
<discriminator type="string"
formula = "(Select a.Name from A a where a.id = id)" />

<subclass name="Book" discriminator-value="BOOK"/>
<subclass name="Newspaper" discriminator-value="NEWSPAPER"/>
<subclass name="XML" discriminator-value="XML">
<join table="XML_DOCUMENTS">
....
</join>
</subclass>

you have 1 a.Name for 1 yourClass.id isn't it?
why do you need another table?

I do not need another table, if that would be my choice.
there already is another table and I need to persist my object to that table schema done by a "idiot ". I cant change it-)))

Formula discriminators are not implemented in Hibernate 2.1. However, it should be an easy job to backport this feature from v22branch, if you really need it. (It is working very nicely in CVS.) I will accept a patch to v21branch if you provide one.

Did somebody patch it? I need to solve the same problem.

Just in case anyone else was wondering about this today as well. You can indeed put in the select statement to pull the discriminator off another table.

In my case I had a type table that has a CLASS_NAME column in order to create the object by reflection.

I wanted to maintain referential integrity so I wanted to hook the FK to the PK of the type table.

I also wanted to use the CLASS_NAME as the discrim in the 'child' table so using



I was able to get exactly what I needed. Learn something new every day with this :D