Casting a CGLIB proxied class

formi05 · **Posted:** Wed May 18, 2005 3:58 am

I recently went through a porting excercise where I was converting a huge domain mode (250+ classes) from using ObjectStore to Hibernate3. This presented some interesting challenges as this model had evolved over 5 years and was in its current state very object oriented. I probably touched most mapping aspect/challenges possible and learned alot about hibernate and ORM/caching/TX in general.

One issue that I found kind of hard to get around was the usage of Proxied classes (all classes by default in Hibernate3 - setting lazy="true") and type casting.

Looking aroung the net I found the recommendation.. specify lazy="false" for those classes where you need to type cast. In my case that meant making all baseclasses non-lazy. I tried that and can only say... bye bye to performance. It just doesnt work. The type of domain model I was working with (not an option to rewrite) I had to find another solution. We are talking a magnitude slower with lazy set to of.

Well I wrote my own narrower that I want to chare with you. Please have a go and see what you think. This utility class retreives that implementation of the proxy and works fine... I am using it at the moment. The performance is great.

Code:

public class ProxyConverter {

   public static Object convert(Object object)
   {
      if (object instanceof HibernateProxy) {
         HibernateProxy proxy = (HibernateProxy) object;
         LazyInitializer li = proxy.getHibernateLazyInitializer();
         return li.getImplementation();
      }
      else {
         return object;
      }      
   }
}

max · **Posted:** Wed May 18, 2005 7:56 am

you dont have to have lazy="false" on your collections, keep those lazy.

btw. what you do below in your code is dangerous since you will be accessing the object directly and thus not guaranteed session scope identity.

formi05 · **Posted:** Wed May 18, 2005 9:47 am

Hi Max, yes that is true, but I have to specify lazy=false on my baseclasses and that in itself caused the whole object graph to be loaded eagerly. It basically killed the app... The whole domain model was based around deeply nested hierachies.

Is there a way to specify laziness for a specifyc sublevel withouth having the whole graph loaded eagely?

Enabling the proxying feature really boosted the application.

The Session identity is important but isnt that associated with the Id property? Another thing to think about here it the dirty detection and updates.

/Mikael

aibrahim · **Joined:** Fri Sep 26, 2003 11:44 am **Posts:** 13

Hi,

Would the maximum fetch depth help? It controls how deep into the sub graph Hibernate will go while loading associated objects.

Regards,

Ali Ibrahim