JPA @OneToMany Question

Question

Hello, there.
How can I set OneToMany relationship in JPA, when child's identity(uniqueness) needs parent's primary key?
Every books that I have only talk about the @PrimaryKeyJoinColumn with OneToOne mapping.
Every books that I have only talk about the @OneToMany mapping with non-identifying relationships.
Every google pages has no exception.
@Entity public class Parent implements Serializable {
    @Id public int id;
    @OneToMany public Collection<Child> child;
@Entity public class Child implements Serializable {
    @Id public int child_id;
    @ManyToOne Parent parent; // NOT FK, BUT PK ?????????????
}

Answer 1

This is something that JPA 1.0 does not handle too well. Hopefully JPA 2.0 will be easier.
Basically you need to duplicate the id field and use a @PrimaryKeyJoinColumn. But some JPA providers have alternatives.
See,
[http://en.wikibooks.org/wiki/Java_Persistence/Identity_and_Sequencing#Primary_Keys_through_OneToOne_Relationships]
The OneToOne would be a ManyToOne for your example, but mainly the same.
-- James : [http://www.eclipselink.org]