Lazy loading with RequestFactory

Question

I'am using GWT 2.4 with Hibernate and RequestFactory and I have queries like this one

contextA.getEntityById(id).with("elements").fire(new Receiver<EntityBaseProxy>() {
        @Override
        public void onSuccess(EntityBaseProxy entity) {
            System.out.println(entity.getElements().size());
  }
});

I'am little confused, when elements, which are the children of the entity, are fetched lazily, I get a NullPointer in System.out.println(entity.getElements().size());

Answer 1

My first solution :

• I kept the Lazy loading on the entity.getElements()
• Add a new transient methode that fetch the elements from the DOA, let call it getElementsFromBd()
• Do the mapping for getElementsFromBd() in the EntityProxy
• In my presenter I called getElementsFromBd()instead of getElementsFromBd()

Presenter

contextA.getEntityById(id).with("elementsFromDb").fire(new Receiver<EntityBaseProxy>() {
    @Override
    public void onSuccess(EntityBaseProxy entity) {
        System.out.println(entity.getElementsFromBd().size());
}
});

Entity model

...
@Transient
public List<Element> getElementsFromDb(){
   doa.getElementsFromDb(this.id);
}
...

Thanks everybody

EDIT

I ended up using a servlet that extends RequestFactoryServlet where I begin and commit the transactions

public class CustomRequestFactoryServlet extends RequestFactoryServlet {

@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    Transaction tx = null;
    try {
        Session session = HibernateUtil.getCurrentSession();
        tx = session.beginTransaction();
        super.service(request, response);
        session.getTransaction().commit();
    } finally {
        if (tx != null && tx.isActive()) {
            tx.rollback();
        }
    }
}

}