Access session scoped bean from request scoped bean

Question

I\'m trying to use a pattern found on a IceFaces page.(I\'m not using IceFaces, using PrimeFaces)

In this case I have two beans:

UserController and

Answer 1

^{(this was originally posted on https://stackoverflow.com/questions/10691324/working-with-3-java-beans-controller-backing-model, but the OP deleted the question and I didn't want to throw away the answer, I think a repost on this question is suitable as well)}

You were probably focusing too much on this ICEfaces blog which contains mainly nonsense.

You should have a single JSF managed bean which acts as a controller, you already have it: UserController. You should have a simple entity bean which represents the model, you already have it: UserVO. You should have an enterprise bean which represents the service, you already have it: UserBO. Those last two doesn't need to be JSF managed beans.

Based on your question history you're using Glassfish, thus you can make use of JPA and EJB. So the model class should be a JPA @Entity and the service class should be a @Stateless EJB.

The use case of a "login user" is however special. You don't want to have the entity as a session scoped managed bean, or it would be implicitly created by JSF. You'd better put it straight in the session scope yourself, so that you can check on #{not empty user} if the user is logged in or not.

All with all it should look something like this:

@Entity
public class User {

    private String username;
    private String password;

    // ...
}

@Stateless
public class UserService {

    @PersistenceContext
    private EntityManager em;

    public User find(String username, String password) {
        return em.createQuery("SELECT u FROM User u WHERE username = :username AND password = MD5(:password)", User.class)
           .setParameter("username", username)
           .setParameter("password", password)
           .getSingleResult();
    }

}

@ManagedBean
@ViewScoped
public class UserController {

    private String username;
    private String password;

    @EJB
    private UserService service;

    public String login() {
        FacesContext context = FacesContext.getCurrentInstance();

        try {
            User user = userService.find(username, password);
            context.getExternalContext().getSessionMap().put("user", user);
            return "/views/commons/home.html?faces-redirect=true";
        }
        catch (NoResultException) {
            context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, "Unknown login, please try again", null));
            return null;
        }
    }

    public String logout() {
        FacesContext.getCurrentInstance().getExternalContext().invalidateSession();
        return "/views/commons/login.html?faces-redirect=true";
    }

    // ...
}

with

Alternatively, you can make the UserController a session scoped bean which holds the User entity, you'd only need to add an extra method to check if the user is logged in or not so that you can use it in EL by #{userController.loggedIn}.

@ManagedBean
@SessionScoped
public class UserController {

    private User user = new User();

    @EJB
    private UserService service;

    public String login() {
        FacesContext context = FacesContext.getCurrentInstance();

        try {
            user = userService.find(user.getUsername(), user.getPassword());
            return "/views/commons/home.html?faces-redirect=true";
        }
        catch (NoResultException) {
            context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, "Unknown login, please try again", null));
            return null;
        }
    }

    public String logout() {
        FacesContext.getCurrentInstance().getExternalContext().invalidateSession();
        return "/views/commons/login.html?faces-redirect=true";
    }

    public boolean isLoggedIn() {
        return user.getId() != null;
    }

    // ...
}

with