Using existing ejb3 entity beans in seam

[renspr]

Hi,

I would like to know how to use existing ejb3 entity beans in seam as a seam component? Lets assume the following scenario:

I have a simple ejb3 package deployed in JBoss, which provides a persistent context (unitName = "openep") and a simple entity bean named User. Lets call this package PACKAGE_A.

The User entity in PACKAGE_A has no @Name and @Scope annotations, so it is not a seam component. For the User entity in PACKAGE_A I don't want to have any dependencies to seam. It is just a plain entity bean.

In a second package (PACKAGE_B), which is actually a seam application packaged as an ear, I want to use the existing entity bean from PACKAGE_A as a seam component. My application in PACKAGE_B is basically equivalent to the seam registration example except that I want to use my existing User entity from PACKAGE_A.

My naive approach to make this existing User entity a seam component was to create a SeamUser class, which extends the existing User entity from PACKAGE_A.

@Name("user")
@Scope(SESSION)
public class SeamUser extends User {

 private static final long serialVersionUID = -6805341268455291354L;

}

My registration action in PACKAGE_B looks like this:

@Stateless
@Name("register")
public class RegisterAction implements Register {

 @In
 @Valid
 private SeamUser user;

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

 @IfInvalid(outcome = Outcome.REDISPLAY)
 public String register() {
 em.persist(user);
 return "success";
 }

}

The deployment of PACKAGE_B works but when I try to register a new user I will get a

 javax.ejb.EJBException: java.lang.IllegalArgumentException: Unknown entity: com.openep.registration.SeamUser

exception when calling em.persist(user). I tried to cast SeamUser to User but this leads to the same exception.

...
em.persist((User)user);
...

The following code works and does exacly what I want, but I like to know if there is a more elegant way to do it?

@Stateless
@Name("register")
public class RegisterAction implements Register {

 @In
 @Valid
 private SeamUser user;

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

 @IfInvalid(outcome = Outcome.REDISPLAY)
 public String register() {
 User myUser = new User(user.getUsername(), user.getPassword());
 em.persist(myUser);
 return "success";
 }

}

I hope that someone can give me a hint.

Best regards, René

[doliver2000]

Even though you have extended an enity bean (User) your SeamUser class will only be an enity bean itself if you annotate it

[norman.richards]

You could use @Unwrap:

@Name("currentUser")
@Scope(ScopeType.SESSION)
public class Foo
{
 User user;

 @Create
 public void createUser() {
 user = new Customer();
 // default intialization maybe
 }

 @Unwrap
 public User getValue() {
 return user;
 }

}

[norman.richards]

Sorry - I hit reply before completing the post.

Anyways, in the above example, you would have an instance of Foo in the session, but when you inject "currentUser", the @Unwrap method will be called and you'll inject the User instance. Like this:

 @In(create=true)
 User currentUser;

That ought to get you by in this case.