OneToOne persisting two objects in a single transaction

[Alessandro Ilardo]

On a facade bean I am trying to persist two objects relationed between eachother as shown belowe

 @Entity
@Inheritance(strategy =InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="user_type", discriminatorType=DiscriminatorType.STRING)
@DiscriminatorValue("basic")
@Table(name="USR")
public class Usr implements java.io.Serializable {
....
@OneToOne(cascade = CascadeType.ALL)
@PrimaryKeyJoinColumn
private UsrRole userRole;
public UsrRole getUserRole() {
return userRole;
}
public void setUserRole(UsrRole userRole) {
this.userRole = userRole;
}
}
@Entity
@Table(name="USR_ROLE")
public class UsrRole implements java.io.Serializable {
....
}

In a facade bean I try to persist them in a single transaction, I'd like to have suggestions on my approach. Is there a better way to do it?

em.getTransaction().begin();
// Persist the user
em.persist(user);
// Persist the role
em.persist(userRole);
em.getTransaction().commit();

Thanks in advance for your suggestions
[ April 18, 2007: Message edited by: Alessandro Ilardo ]

[Mark Spritzler]

How about

em.getTransaction().begin();
// Persist the user
user.setUserRole(userRole);
em.persist(user);
em.getTransaction().commit();

The cascade option of All in the User mapping should automatically insert the UserRole too when persisting the User, that is what Cascade options are all about.

Mark

[Mark Spritzler]

"On a facade bean"

Why that just flew right by me the first time I read your post.

Wouldn't you want that kind of method in a DAO object? And not tie EJBs or your facade bean to JPA?

Mark

[Alessandro Ilardo]

thanks for your reply Mark,
As the user must have one relation with a row in the USR_ROLE, I created a constructore like:

public Usr(String username, String password, String email,
UsrRole userRole) {
this.setUsername(username);
this.setPassword(password);
this.setEmail(email);
this.setUserRole(userRole);
}

from the client I run

UsrRole role = new UsrRole();
role.setRoleGroup("users");
role.set_role("testRole");
role.setUsername("fakeUser");
UsrAddress firstAddress = new UsrAddress();
firstAddress.setFirstName("fakeName");
firstAddress.setLastName("fakeSurname");
firstAddress.setTitle("Mr.");
firstAddress.setWebsite("http://www.yourWebSite.com");
firstAddress.setPostalCode("LN6 FD6");
Usr user = new Usr("fakeUser","00000000","[e-mail]",role);

and the EJB

em.persist(user);
and it partially works.

But I'm getting different values from the Primary Keys. I expected to find the same key in both records.

About the DAO.
I used that pattern when I had to write SQL querys, since I've started with EJB3 I'm using a stateless bean to access entity's.
Wrong approach?
Thanks again.

[Mark Spritzler]

Each table has their own primary key, they wouldn't necessarily have the same ID, you can map so that the two records share the same PK, but I don't remember of the top of my head the mapping to do that.

I still like the model of seperating EJB business logic from Data Access logic. I also still like the idea of even not putting code directly in Beans, but other POJOs, but there is also a way to do that with having your Bean extend the POJO. But having the business logic in the Bean isn't wrong anymore. Since that POJO with the EJB annotations can still work outside the container.

Mark