I have a scenario I'm not sure how to handle in the mapping. I have the following structure:

abstract class baseClass{...}

class Persistable1 : baseClass{...} (has typeValue=1)

abstract class subBaseClass : baseClass {...}
(properties map to a second table, as in joined-subclass)

class Persistable2 : subBaseClass{...} (has typeValue=2)
class Persistable3 : subBaseClass{...} (has typeValue=3)

I see from the documentation that joined-subclasses and subclasses can't mix and match, however Persistable1 class doesn't have any additional properties so can't be a joined-subclass.

How can I represent this in the mapping file?

While it's true that you can't mix subclass and joined-subclass for decendents of a single base class (you have to choose one or the other) it actually is possible to have joined-subclasses that don't have any additional properties. I've actually done exactly that.

That irritating part is that you have to have a separate table for every joined-subclass, so for empty ones the table must exist with nothing but an Id in it, but it's a good start in the event that you're expecting to expand the class's properties in the future.

Cheers,

Symon.[/i]

To the NHibernate Team, which are the possibilities of seeing such feature implemented in future versions.
I think this is a really needed feature.
Thanks.

What you can do is:
- Create a JIRA issue for that: http://jira.nhibernate.org/
- Post its link here
- Vote for it :)

JIRA ISSUE
http://jira.nhibernate.org/browse/NH-424
Please VOTE!!! :D

See new comments on http://jira.nhibernate.org/browse/NH-424