Hibernate OneToOne attempted to assign id from null one-to-one property

Question

I'm trying to create a one to one relationship between 2 entities where the "child" is referenced by the "parent" id as foreign key. Here's my 2 entities:

@Entity
@Table(name = "users")
public class User extends PanacheEntityBase implements Serializable {

    @Id
    @GeneratedValue(generator = "UUID")
    @GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
    String id;

    @OneToOne(mappedBy = "user", cascade = CascadeType.ALL , optional = false)
    Profile profile;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public Profile getProfile() {
        return profile;
    }

    public void setProfile(Profile profile) {
        this.profile = profile;
    }
}

and

@Entity
@Table(name = "profiles")
public class Profile extends PanacheEntityBase implements Serializable {

    @GenericGenerator(name = "generator", strategy = "foreign",  parameters = @Parameter(name = "property", value = "user"))
    @Id
    @GeneratedValue(generator = "generator")
    @Column(name = "user_id")
    String id;

    @OneToOne
    @MapsId
    @JoinColumn(name = "user_id")
    User user;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

On save I build the object and persist it:

    User user = new User();
    Profile profile = new Profile();
    user.setProfile(profile);
    userRepository.persist(user);

but I get this error

org.jboss.resteasy.spi.UnhandledException: javax.persistence.PersistenceException: org.hibernate.id.IdentifierGenerationException: attempted to assign id from null one-to-one property [com.myne.entities.Profile.user]

What am I doing wrong?

Your setup is a bit odd, is the PK of a profile the ID of the user? — Smutje, Nov 04 '20 at 11:33
@Smutje the idea is that user and profile have the same pk, unless it's not possible and there are other approaches — user3353167, Nov 04 '20 at 11:38
Can you try to remove all annotations from `Profile.id` apart from `@Id` and `@Column`? I don't think `@GenericGenerator` and `GeneratedValue` are necessary (see also https://thorben-janssen.com/hibernate-tips-same-primary-key-one-to-one-association/) — Smutje, Nov 04 '20 at 11:49
@Smutje unfortunately even following exactly what he does I still get the same problem — user3353167, Nov 04 '20 at 12:01
Okay, probably it has something to do with your `org.hibernate.id.UUIDGenerator` but that's beyond my knowledge of JPA (or Hibernate in that case) :-) — Smutje, Nov 04 '20 at 12:02

score 3 · Answer 1 · answered Nov 04 '20 at 14:25

So after more research I finally was able to deal with the problem. I used an hybrid between these 3 posts

https://howtodoinjava.com/hibernate/hibernate-one-to-one-mapping/

https://stackoverflow.com/a/52010963/3353167

https://stackoverflow.com/a/18622821/3353167

As suggested on the first post, using @MapsId will let hibernate know that the child entity will share the parent's id. So I changed my classes to:

@Entity
@Table(name = "users")
public class User extends PanacheEntityBase implements Serializable {

    @Id
    @GeneratedValue(generator = "UUID")
    @GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
    String id;

    @OneToOne
    @MapsId
    Profile profile;

    ...

And

@Entity
@Table(name = "profiles")
public class Profile extends PanacheEntityBase implements Serializable {

    @Id
    @Column(name = "user_id")
    String id;
    
    // removed the User Column
    ...

The issue then comes from Hibernate using GenerationType.Auto as suggested in the third post. So to instruct Hibernate to generate a UUID instead, I followed the example in the second post and changed the Profile id to look like:

@GeneratedValue(generator = "UUID")
@GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
@Column(name = "user_id", updatable = false, nullable = false)
@Id
String id; 

...

It worked like a charm. I hope it will help anyone else facing the same problem in the future

I'm sorry, but does this mean you couldn't have a bi-directional relationship between User and Profile? Like: User has a Profile, but you cannot get a User if you only have a Profile? — Voronin, Jul 29 '21 at 16:07

Hibernate OneToOne attempted to assign id from null one-to-one property

1 Answers1