My understanding of how Polymorphism="explicit" works might be flawed so someone bring me back to reality here:

In a situation as shown below in:

ClassA <-- ClassB

where ClassB derives from ClassA and ClassA is mapped with the attribute Polymorphism="explicit"; When I formulate a query with the predicate "FROM ClassA as A WHERE A.SomeProperty > 4" I should get in my resultset only instances which are explicitly of type ClassA right? I shouldn't get any ClassB instances.

If this is not true, or if I have missed some crucial point, someone please set me straight. If this is true and I haven't missed anything I have an example which perplexes me that I will post as a response.


Hibernate version: NHibernate-1.2.0.Alpha1-debug

So, I found my answer in the following thread in the Hibernate forum:

http://forum.hibernate.org/viewtopic.php?t=399&highlight=explicit+polymorphism

It looks like the class attribute polymorphism='explicit' has absolutely no effect on class hierarchies with subclasses mapped with <joined-subclass> but rather only on class hierarchies with classes mapped as <subclass> using the table per class hierarchy approach. To get the behavior I described in my first post it looks like you would formulate an HQL query as follows:

FROM ClassA as c WHERE c.class = MyNamespace.ClassA

this filters the list of returned object instances to be only those which are explicitly ClassA instances and not also ClassB instances etc.

Hope this helps someone.[/url]