Hibernate version: 3


Hi,

I'm new to Hibernate and have a question around inheritance.

I've a base Java abstract class called User. Three classes extend from this but don't contain any additional data themselves, just different methods.

All 3 are stored in a table in the database called User.

Is it possible to create one mapping file for User to cover all 3 sub-classes?

If so, what do I need to do then in my code to get this to work?

Thanks.

I've not done this, but a few days ago I came across something that sounds similar to your requirements. In this example, they have 1 database table and multiple descendents use it.

http://www.hibernate.org/hib_docs/v3/re ... tance.html

9.1.7. Mixing implicit polymorphism with other inheritance mappings
There is one further thing to notice about this mapping. Since the subclasses are each mapped in their own <class> element (and since Payment is just an interface), each of the subclasses could easily be part of another inheritance hierarchy! (And you can still use polymorphic queries against the Payment interface.)

<class name="CreditCardPayment" table="CREDIT_PAYMENT">
<id name="id" type="long" column="CREDIT_PAYMENT_ID">
<generator class="native"/>
</id>
<discriminator column="CREDIT_CARD" type="string"/>
<property name="amount" column="CREDIT_AMOUNT"/>
...
<subclass name="MasterCardPayment" discriminator-value="MDC"/>
<subclass name="VisaPayment" discriminator-value="VISA"/>
</class>