Question

Currently I have a structure like this:

A | +--B | +--C 

It’s mapped with one table per subclass using joined tables. For historic reasons I also use a discriminator, so the current situation is as described in Section 9.1.3 of the Hibernate manual.

Question: How do I extend the mapping for a structure like this:

A | +--B |  | |  D | +--C 

Can I <subclass> a <subclass> in the hibernate mapping? What <key>s do I need?

Answer 1

not tested but, according to the link you posted if you are using hibernate3

<hibernate-mapping>   <class name='A' table='A'>     <id name='id' type='long' column='a_id'>       <generator class='native'/>     </id>     <discriminator column='discriminator_col' type='string'/>     <property name='' type=''/>     <!-- ... -->   </class>   <subclass name='B' extends='A' discriminator-value='B'>     <!-- ... -->   </subclass>   <subclass name='D' extends='B' discriminator-value='D'>     <!-- ... -->   </subclass>   <subclass name='C' extends='A' discriminator-value='C'>     <!-- ... -->   </subclass> </hibernate-mapping>