JPA and JSF: right way of injecting EntityManager

Question

It has been some hours I\'m working on this but still I haven\'t figured out what is the right way of using JPA with JSF.

I have a session scoped managed bean that can d

Answer 1

I'm an idiot. I've already clashed with this problem in the past but I forgot.

To everyone that steps here with the same problem here is the solution. Container Managed Transactions only works if the container is an EJB. It does NOT works if the container is JSF! It doesn't matters how you inject your entity managers, injections succeed but the created object will not works.

The way of solving it, is creating an EJB DAO object that deal with the database for you. Something like

@Named
@Stateless
public class MyDAO {

@PersistenceContext(unitName = "SRA")
private EntityManager em;

public void save(Object o) {
    em.persist(o);
    em.flush();
}

}

and then injecting those object inside your managed bean like this:

@ManagedBean
@SessionScoped
public class MyManagedBean {
@EJB
private MyDAO dao;

public void action() {
....
    dao.save(o);
}

}

injecting directly an EntityManager into a Managed Bean will give you a Transaction Required Exception.

I'm still unsure about injecting something like that into a broader scoped bean. I will look into this later.

Answer 2

"someone tells that I have to inject the EM directly into my managed beans using the PersistenceContext annotation."

If you look at the Java EE tutorial, that's exactly what they do

@Singleton
public class MyUserDatabaseEntityManager { 
    // declare a producer field 
    @Produces
    @UserDatabase
    @PersistenceContext
    private EntityManager em;
}

@ConversationScoped
@Stateful
public class RequestBean {

    @Inject
    @UserDatabase
    EntityManager em;

This may not completely answer your question, but hope it helps.