Bidirectional and EmbeddedId

ruig · **Posted:** Sun Mar 21, 2010 10:23 am

Hello,

I have model (simplified version described below) and cannot configure bidirectional association.

Exactly to say — I can access A and B from Bind class (Bind freshly fetched from DB).
But I cannot access Binds neither from A or from B (A and B freshly fetched from DB).

getBindings always returns null though mappedBy properly set.

I tried without EmbeddedId - an it works in both directions.

What is wrong in my config?

Many thanks

Code:

@Entity
class A {
  @Id
  private Integer id;
  @OneToMany(mappedBy = "key.a")
  private Collection<Bind> bindings;
}

@Entity
class B {
  @Id
  private Integer id;
  @OneToMany(mappedBy = "key.b")
  private Collection<Bind> bindings;
}

@Entity
class Bind {
  @EmbeddedId
  private BindPK key;
  @Basic
  private String bindProperty;
}

@Embedded
class BindPK {
  @ManyToOne
  private A a;
  @ManyToOne
  private B b;
}

ruig · **Posted:** Sun Mar 21, 2010 12:27 pm

Solution found in internet — usage of @IdClass instead of @EmbeddedId

Code:

@Entity
class A {
  @Id
  private Integer id;
  @OneToMany(mappedBy = "a")
  private Collection<Bind> bindings;
}

@Entity
class B {
  @Id
  private Integer id;
  @OneToMany(mappedBy = "b")
  private Collection<Bind> bindings;
}

@Entity
@IdClass(BindPK.class)
class Bind {
  @Id
  private A a;
  @Id
  private B b;
  @Basic
  private String bindProperty;
}

@Embedded
class BindPK {
  @ManyToOne
  private A a;
  @ManyToOne
  private B b;
}