Twitter like relationships in JPA - database

Question

I'm getting into problems with JPA. I'm trying to implement a database that allows users to follow other users and be followed.
I think I'd need (summing up) something like this:
USER_TABLE: id | userName
RELATIONSHIP_TABLE: id | follower | followed | acceptation
I have two entities (also summed up):
#Entity
public class User implements Serializable {
#Id
private Long id;
private String userName;
#OneToMany
private Collection<Relationship> followings;
}
#Entity
public class Relationship implements Serializable {
#Id
private Long id;
private User follower;
private User followed;
private boolean accepted;
}
My problem is that I'm not sure if it's possible to do this, because I obtain more tables that the two that I need.
Can anybody help me?
Thanks and sorry about my english.

Answer 1

You obtain more tables because you did not make the associations bidirectional. JPA has no way to know that Relationship.follower is the other side of the User.followings if you don't tell:
#Entity
public class User implements Serializable {
#OneToMany(mappedBy = "follower")
private Collection<Relationship> followings;
// ...
}
#Entity
public class Relationship implements Serializable {
#ManyToOne
#JoinColumn(name = "follower")
private User follower;
#ManyToOne
#JoinColumn(name = "followed")
private User followed;
// ...
}
The documentation of course explains how that works.