Table per concrete class inheritance mapping query

stolley · **Posted:** Mon Dec 22, 2003 1:08 am

I'm using Hibernate 2.1.1.

I've been reading Chapter 16 - Inheritance Mappings, and it says something I don't understand.
I'm primarily interested in the section that deals with using a table-per-concrete-class strategy.

This section seems to say that if I have two normally mapped classes (unrelated) and have them both implement the same (unmapped) interface, then they are now part of a table-per-concrete-class mapping?

It then goes on to say (last paragraph of 16.1):

Quote:

If we execute a query against the Payment interface - for example, from Payment - Hibernate automatically returns instances [of the concrete classes]

I'm trying to simplify this situation down (no mappings from other entities to the interface, no properties on the interface), but it's not working for me.
I get an exception:

Code:

 net.sf.hibernate.QueryException: unexpected token: as [from ElvasContact as contact]

Am I mis-understanding the documentation? Or am I simplifying the example down too much (maybe I need to have a property declared on the interface)?

stolley · **Posted:** Mon Dec 22, 2003 1:30 am

Actually, turns out it works.

You just can't use an unqualified classname; for normal classes you can just use the classname (as long as you don't have duplicate classnames and have Hibernate configured appropriately), but for this kind of un-mapped superclass, you seem to need to use the fully qualified classname.

Might be worth noting in the doco (or is it already documented somewhere else, in which case sorry for the noise)?

stolley · **Posted:** Mon Dec 22, 2003 2:22 am

Also, I get:

Code:

net.sf.hibernate.MappingException: No persister for: nrm.clas.domain.elvas.contact.ElvasContact

when I try to use the interface class in a Criteria query.

Is it not possible to use these unmapped superclasses in Criteria queries, or am I doing something wrong (again)?

stolley · **Posted:** Sun Jan 04, 2004 6:59 pm

<bump>

So how about it?
Is it not possible to query with these "unmapped superclass" type objects using the criteria API?

emmanuel · **Posted:** Sun Jan 04, 2004 7:03 pm

Criteria API is a subset of HQL, add an issue to JIRA please.

michael · **Posted:** Sun Jan 04, 2004 7:05 pm

If I read the source correclty, the criteria API in the moment just works for mapped classes, this might be worth a JIRA entry.

stolley · **Posted:** Tue Jan 06, 2004 1:20 am

Created HB-608: http://opensource.atlassian.com/project ... key=HB-608

There's a dodgy patch attached that kind of does the job in the same way as the HQL code does (two queries, unioned in java land).