I have a hierarchy of classes using the table-per-subclass strategy, when i use the Load() method to get a persistent class specifying the top class of the hierarchy i obtain a Proxy.
If i use NHibernateUtil.GetClass() with the Proxy it returns the right Type of the class (a child class), but if i try to cast it to that Type i get an error, i dont know how to cast to the real class?

Here's an example:


If i use Get() instead of Load() it returns a instance of the real class, its that the solution?


Hibernate version: 1.2.GA
.NET Framework: 1.1

see http://www.hibernate.org/hib_docs/nhibernate/1.2/reference/en/html_single/#performance-fetching-proxies

This is why I personally do not use proxies for types which use inheritance. Not being able to use == is what bothers me the most, not the casting, but the casting could also be an issue.

If you use Load for the correct subclass of the same objectit will return the correct proxy. From the documentation (in section 15.1.3 of the 1.2.0 docs):

<snip>

There are some gotchas to be aware of when extending this approach to polymorphic classes, eg.



Firstly, instances of Cat will never be castable to DomesticCat, even if the underlying instance is an instance of DomesticCat:



Secondly, it is possible to break proxy ==.


However, the situation is not quite as bad as it looks. Even though we now have two references to different proxy objects, the underlying instance will still be the same object:


</snip>

The key part is:

DomesticCat dc =
(DomesticCat) session.Load(typeof(DomesticCat), id); // acquire new DomesticCat proxy!

Note that this will not actually hit the DB again - it will just create a new proxy for the underlying object that's already in the session. Using this will break == but if that's not a problem at least it solves your other problem! :)

Cheers,

Symon.

thanks to all

merge_s.rottem, what you say solve my problem, and if doesnt exist a better way i gona use it. But if i use Get() instead of Load() it returns the right class, its a valid solution too?

jchapman, what's the way to avoid proxys for classes which use inheritance? i know one way is no using lazy init in many-to-one and one-to-one relationship, but in a Polymorphic Load? using Get()?

Sorry my english and thaks for your time.

Just put lazy="false" in your mapping file for all class/subclass/joined-subclass entries in the inheritance chain. Whenever you load using Get() or Load() it will pull the real class, not the proxy.

thanks again jchapman, i didnt know i can do that.