Just want to have some clear ideas on proxies and polymorphic classes.

It seems there is some problem using proxies with polymorphic class. If I load a base class proxy, I cannot cast it to the subclass even if the underlying instance is an instance of the subclass.

In my case, this breaks my equals method because I do an instanceof check in it.

I understand why, but I just want to know the recommended workaround. Does that mean that I must not use proxies with polymorphic classes (or that it is not recommended).

If this is the solution I just want to raise a possible problem with the next version of hibernate. On the dev mailing list gavin said that lazy will be the default behaviour for classes in this next version. This could lead in confusing bugs for people who did not uses proxies in the past and will see strange equals behaviour on their polymorphic classes in the future.

seb

I'm using proxies with polymorphic objects and haven't had the trouble you describe. I have seen some problems when querying the data using HQL. Polymorphic queries are discussed in the reference manual, albeit quite lightly:

http://www.hibernate.org/hib_docs/reference/en/html_single/#queryhql-polymorphism

Probably the difficulty lies in the fact that you've got a proxy on the base class. Try not defining a proxy for the base class and ONLY put the proxy on the sub-classes. The reason is that when class enhancement occurs, it creates a descendent of the enhanced class (no magic here, just plain old sub-classing). That enhanced class would be a sibling of your sub-classes, not an ancestor.

In order to get the polymorphism right you also might have to experiment with explicit polymorphism, described in:

http://www.hibernate.org/hib_docs/refer ... tion-class

under implicit vs. explicit polymorphism (do a search).

With this kind of relation I cannot avoid proxy on the base class. This is the situation where I got the problem