JPA - @OneToOne relation on non-primary-key field

Question

I have a Spring Data JPA backend using Hibernate as the ORM implementation.

This is the model:

 __________     _________________________
 |Person  |     |MailConfig             |
 |________|     |_______________________|
 | id PK  |     | uid PK-FK(Person.uid) |
 | uid    |     | ...                   |
 | ...    |     |                       | 
 |________|     |_______________________|

@Entity
@Table(name="Person")
public class PersonEntity{

    @Id
    private String id;

    private String uid;

    @OneToOne(mappedBy="id", fetch=FetchType.EAGER)
    private MailConfigEntity mailConfigNotes;

    ...
}

@Entity
@Table(name="MailConfig")
public class MailConfigEntity implements Serializable{

    @Id
    @OneToOne
    @JoinColumn(name="uid", table="Person", referencedColumnName="uid", insertable = false, updatable = false)
    private PersonEntity id;

    ...
}

Person table is joined with MailConfig table through a field that is not Person's primary key. When I load an entity using personDAO.findOne(id) I can see the join in the query is performed against person.id instead of person.uid (on personent0_.id=mailconfig2_.uid). Any idea why this isn't working?

Query log:

    select
        personent0_.id as id8_2_,
        personent0_.uid as uid8_2_,
        mailconfig2_.uid as uid5_1_
    from
        Person personent0_ 
    left outer join
        mailconfig mailconfig2_ 
            on personent0_.id=mailconfig2_.uid 
    where
        personent0_.id=?

Answer 1

As per the documentation, check if this is a foreign key

There are three cases for one-to-one associations: either the associated entities share the same primary keys values, a foreign key is held by one of the entities (note that this FK column in the database should be constrained unique to simulate one-to-one multiplicity), or a association table is used to store the link between the 2 entities (a unique constraint has to be defined on each fk to ensure the one to one multiplicity).

Also the JoinColumn should be on the owner side of the relationship