Transaction using JSF2, EJB3, JPA2 - jpa

Question

What is the best way to handle transactions in this environment?
I have a Transacao class, which has a collection of Transacao.
public class Transacao {
#OneToMany(fetch = FetchType.LAZY, mappedBy = "pai")
private List<Transacao> filhos;
}
I load this in JSF from a EJB, something like:
public class TransacaoBean {
#EJB
private TransacaoService transacaoService;
private void edit(Long id) {
this.transacao = transacaoService.findById(id);
}
}
although, if I want to get the collection of filhos, I have to do this:
public class TransacaoBean {
...
private void edit(Long id) {
this.transacao = transacaoService.findById(id);
log.info(this.transacao.getFilhos.size()); //this throws a LazyInitializationException
}
}
and I get an Exception.
What is the best way to have this loaded in my JSF? I'm considering creating a Filter and using USerTransaction to keep the transaction open for the request or fetching the filhos in my EJB. Is there a better solution to this, which one is better?

Answer 1

The fetch's default value of the #OneToMany is FetchType.LAZY.
You can set it FetchType.EAGER to use them in non-managed environment.
Or you can make another EJB or method for getting a list or just the size.
public class TransacaoService {
public Transacao findById(final long id) {
...
}
public long getFilhosSize(final long id) {
// SELECT f FROM Transacao AS t WHERE t.pai.id=:id
}
#PersistenceContext
private EntityManager entityManager;
}