I am having trouble setting up a very simple example. I end up with unfixable proxy classes. I have enabled Lazy associations, as recommended. I have not found any good, simple examples, so I suspect a magic option is missing.

Given

@Entity
public class Event {
@Id @GeneratedValue
Long id;
@Column
String title;
@OneToMany(mappedBy="event", fetch=FetchType.LAZY)
Set<Activity> activities = new HashSet();
public Event getThis() {return this;}
}

and

@Entity
public class Activity {
@Id @GeneratedValue
long id;
@ManyToOne(fetch=FetchType.LAZY)
Event event;
@Column
String name;
}

Then

Event event2bPre = (Event)session.get(Event.class, 2L);
Activity act4bPre = (Activity)session.get(Activity.class, 4L);
assertEqual("Second Event", act4bPre.event.title);

Works.

But

Activity act4b = (Activity)session.get(Activity.class, 4L);
assertTrue(act4b.event.getClass().getName()
.contains("Event$$EnhancerByCGLIB")); // Ahh!
Event event2aPost = (Event)session.get(Event.class, 2L);
asertTrue(null == act4b.event.title);

Does not work -- act4b.event.title should not be null.

I think that the weird proxy class is to blame. I have sometimes
even got Entity.getThis() != this in other examples.

The definitions for the classes are as recommended by the book,
AFAIK. I suspect that the annotations are not properly
supported/documented, and have weird JPA issues, and so I would
probably be better off sticking to XML. (Have not tried.)

All help appreciated.

(These sort of issues just cannot happen in SimpleORM.)

Anthony

Hi,

do you also have getters? I am not sure right now whether act4bPre.event.title would de-proxy your entity. The class name Event$$EnhancerByCGLIB is also expected when cglib is used for byte code enhancement.

You could try to use javassist as byte code provider (in fact that is the default provider in the latest version of Hibernate) or you could use lazy loading via interception.

Last, but not least you could try to de-proxy the instance manually. Have a look at this thread: http://forum.hibernate.org/viewtopic.php?t=962876.

The mapping looks otherwise ok. Is there are particular problem you are trying to solve?

--Hardy

Thanks for your reply.

I think that the rule with Hibernate is that you Must always use get methods, unlike POJOs. (I usually do not bother with package local fields.) But it is weird that the second get does not resove things.

Also, is this an effect of using Annotations instead of XML?

I did not see this documented in the book.

Anthony

I am not quite sure what you refer to here.


No, xml vs. annotations is just about how Hibernate gets configured. Under the hood it is always the same core.

--Hardy