migrating from 2 to 3: instanceof results change

peterpumpkin · **Posted:** Fri Jun 03, 2005 7:27 am

I have an abstract class A and a concrete subclass B. These are mapped as follows:

Code:

<class name="A" table="ta">   
  <subclass name="B" discriminator-value="B" proxy="B">

Say that I have an instance of B, sampleB, with id 1. By doing

Code:

A sampleA = (A)session.load(cls, new Integer(1));

if I ask

Code:

sampleA instanceof B

using hibernate 2, I get "true", using hibernate 3, I get "false". Both version use the same classes, server, hibernate configuration, appServer, data.

Tracing the load process, the object sampleA returned is actually in both cases an instance of B proxied by CGLIB,
i.e. an

B$$EnhancerByCGLIB$$75bc@3590"B@6fa"

In the migration guide, if I understood correctly, the only reported change which may affect this is the lazy="false" attribute, but by setting it, the issue above remains.

Is it possible to get consistent answers ?

emmanuel · **Posted:** Fri Jun 03, 2005 9:35 am

which one did you lazy="false"?

peterpumpkin · **Posted:** Fri Jun 03, 2005 9:37 am

For the moment I did it this way, but its ugly:

Code:

   /**
   * beware: persistentObject will be initialized
   */
  public static boolean instanceOfPersistent(Object persistentObject, Class aClass) {

    boolean result = false;
    Class pClass = null;
    if (persistentObject instanceof HibernateProxy) {
      HibernateProxy proxy = (HibernateProxy) persistentObject;
      AbstractLazyInitializer li = (AbstractLazyInitializer) proxy.getHibernateLazyInitializer();

      //this does not work
      //Class bclass = HibernateProxyHelper.getClassWithoutInitializingProxy(persistentObject);
      // hence I use this which is quite ugly, as I fear the object is uselessly initialized:      
      pClass = li.getImplementation().getClass();
    } else
      pClass = persistentObject.getClass();

    if (ReflectionUtilities.getInheritedClasses(pClass).contains(aClass))
      result = true;
    else
      result = false;
    return result;
  }

peterpumpkin · **Posted:** Fri Jun 03, 2005 9:46 am

Answer to Emmanuel:

first I put lazy="false" on B, no improvements;

then I put lazy="false" on both A and B, no improvements;

then I put lazy="false" only on A, and.. it works!

emmanuel · **Posted:** Fri Jun 03, 2005 9:46 am

this does not answer my question

peterpumpkin · **Posted:** Fri Jun 03, 2005 10:16 am

So the final question is: is there a way to be sure that instanceof gives me the correct answer, keeping my objects lazy ? in previous versions of my horrible hack above, I tried to access the "target" field of the proxy, and asking its class, instead of forcing initialization, but even using reflection and extension tricks it has been carefully protected, via privateness and final classes.

Thanks.

emmanuel · **Posted:** Mon Jun 06, 2005 6:28 am

Hibernate.getClass()
but is will initialize the proxy by side effect. This is not what you want.