Question

I’m a bit unfamiliar with the terms necessary to ask this question, but we’ll see if I can get it right.

I have a JPA Entity that represents a joining of several other Entities, which is called UserJump:

@Entity
public class UserJump extends Model{

    @ManyToOne
    public User user;
    @ManyToOne
    public JumpSession jumpSession;
    @ManyToOne
    public Parachute parachute;
}

I have a JumpSession class that refers back to UserJump:

@Entity
public class JumpSession extends GenericModel{

    @OneToMany(mappedBy="jumpSession")
    public List<UserJump> userJumps;
}

However, I need to be able to delete JumpSession objects while retaining any UserJump objects that refer to them(right now I get a ConstraintViolationException when I call delete() on a JumpSession), since the UserJump object still links together other unique information. Ideally, the jumpSession variable in UserJump would be changed to null.

How can I do this?

Answer 1

You just need to modify the UserJump before deleting the JumpSession:

for (UserJump uj : jumpSession.getUserJumps()) {
    uj.setJumpSession(null); 
    // now the UserJump doesn't reference the soon-to-be-deleted JumpSession anymore
}
session.delete(jumpSession);

(note: the above is traditional Java Hibernate code. I don’t know how to translate that in Play’s way of doing)