JPA Bidirectional Relationship

Question

I am trying to establish Bidirectional Relationship between User and Address,

User 1---------->*Address

But

Address 1 -------> 1 User

On referring the internet I got these information

For one-to-one bidirectional relationships, the owning side corresponds to the side that contains the corresponding foreign key
The inverse side of a bidirectional relationship must refer to its
owning side by use of the mappedBy element of the OneToOne,
OneToMany, or ManyToMany annotation. The mappedBy element designates the property or field in the entity that is the owner of the
relationship.

But If I proceed as per information then

I need to use Mapped By on User Entity where Set <Address> hold OnetoMany mapping At the same time I need to use Mapped By on Address Entity where user holds OnetoOne mapping

Note : But @JoinColumn on Address entity for user works fine. If I use mappedBy on either User Entity or Address Entity I got the exception stating that

"The attribute [addresses] in entity class [class com.entity.User] has a mappedBy value of [User] which does not exist in its owning entity class [class com.entity.Address]. If the owning entity class is a @MappedSuperclass, this is invalid, and your attribute should reference the correct subclass."

I am confused on how to use mapped By for this type of Bi-directional relationship.

Update :

<pre>
@Entity
public class User {
    @Id
    @GeneratedValue(strategy= GenerationType.AUTO)
    protected Long id;
    ...
    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY,mappedBy="user")
    private Set<Address> adresses;
} 


@Entity
public class Address {
    @Id
    @GeneratedValue(strategy= GenerationType.AUTO)
    protected Long id;
    ...
    @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JoinColumn(name = "userid", nullable = false)
    private User user;
}
</pre>

Post your User and Address classes or at least relevant parts of it with annotations. It will be easier to see what's the problem. — Piotr Nowicki
I've posted an answer, have a look at my answer on this other question (scroll down on the question until after the accepted answer to see my post there as well) for some more info on what the owning side means, how to use it, pitfalls, etc -> stackoverflow.com/questions/2749689/… — Angular University
@jhadesdev : The link provided by you describes the usage of the mappedBy using an example of ManyToOne and OneToMany. But in my case its ManyToOne and OneToMany — Dineshkumar
If a User has many Addresses, the inverse relationship by definition is a ManyToOne- Many Addresses reference a single User. In the database, this would mean the Address table had a foreign key to the User table. See wiki.eclipse.org/EclipseLink/UserGuide/JPA/… for an example and explanation, but the answer given by jhadesdev seems correct. — Chris

Angular University Angular University · Accepted Answer · 2014-04-16T22:08:35

The problem is that @OneToMany can only have as inverse @ManyToOne, and not @OneToOne. @OneToOne can only have as mappedBy another @OneToOne, check the javadoc for those methods.

The mapping bellow gives you the meaning you want: one user can have many addresses, but an address can only refer to only one user using the id in the foreign key specified in @JoinColumn:

@Entity
public class User {
    @Id
    @GeneratedValue(strategy= GenerationType.AUTO)
    protected Long id;
    ...
    @OneToMany(mappedBy="user")
    private Set<Address> adresses;
} 


@Entity
public class Address {
    @Id
    @GeneratedValue(strategy= GenerationType.AUTO)
    protected Long id;
    ...
    @ManyToOne(optional=false)
    @JoinColumn("your_foreign_key_name")
    private User user;
}

JPA Bidirectional Relationship

1 Answers