EclipseLink - oneToMany in lazy + join fetch

Question

Hi,
I have a little problem with use a "join fetch".
How use join fetch with @OneToMany lazy relations ?
I have two objetcs : Object A has a list of objects B.
A
@oneToMany (Lazy relation)
List<B> listB
Now, I want load these 2 objects.
I write a jpql like "select a from A a left join fetch a.listB where a.id=?"
The sql generated is fine, I see the join between table A and B.
BUT, when I try to access listB (outside session), I have a lazy exception.
Why ?
If (inside session) I access to listB, it's ok (with no more sql).
So, I have wrote a method like that :
public A findA(lond id){
Query q = createQuery(select a from A a left join fetch a.listB where a.id=id");
A = q.getSingleResult();
A.getListB().size() -> to initialize relation (but non sql generated)
return A;
Someone has an idea ?
Thanks for your responses.

Answer 1

Hi,
In fact my method findA... is inside a stateless bean.
Outside session means that I call my method by a client application like that :
Service service= (Service )context.lookup("xxxxx");
A = service.findA();
A.getListB().size;
Exception is
Exception [EclipseLink-7242] (Eclipse Persistence Services - 2.0.2.v20100323-r6872): org.eclipse.persistence.exceptions.ValidationException
Exception Description: An attempt was made to traverse a relationship using indirection that had a null Session. This often occurs when an entity with an uninstantiated LAZY relationship is serialized and that lazy relationship is traversed after serialization. To avoid this issue, instantiate the LAZY relationship prior to serialization.
For the version of eclipseLink, it's an ejb deployed on embedded weblogic with jdeveloper Studio Edition Version 11.1.1.3.0.
It's JPA 1.0.
Thanks for your response.
Hope this help.
Nicolas
Edited by: 865770 on 15-juin-2011 8:12