Spring Data. Repository returns wrong Id (entity data is correct)

yazabara :

Good day, here is problem: CrudRepository returns wrong Id for entities.

Here is base JPA user entity:

@Data
@Entity(name = "user")
@EqualsAndHashCode(exclude = {"roles", "password", "data"})
@ToString(exclude = {"roles", "password", "data"})
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @OneToOne(mappedBy = "user", fetch = FetchType.LAZY)
        private SomeData data;
...

There is a relation one-to-one to some data entity.

@Data
@Entity(name = "some_data")
@TypeDefs({
        @TypeDef(name = "jsonb", typeClass = JsonBinaryType.class)
})
@ToString(exclude = {"user", "views", "biData"})
@EqualsAndHashCode(exclude = {"user", "views", "biData"})
public class SomeData {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @OneToOne
    @MapsId
    private User user;
...

And there is crud repository:

@Repository
public interface SomeDataRepository extends CrudRepository<SomeData, Long> {

    Optional<SomeData> findByUserId(Long userId);
}

Method findUserById returns correct SomeData entity from DB, but this entity has the same ID with userId... And because of it I can't do other activities (insert or update on table "public_view" violates foreign key constraint "fk_view_to_some_data")

It's quite strange.

Alexandru Somai :

The problem could be because you use the @MapsId annotation. Here's what the value of the annotation does, as per Javadoc:

The name of the attribute within the composite key to which the relationship attribute corresponds. If not supplied, the relationship maps the entity's primary key.

You could try to set a specific value to your annotation, or map differently your one-to-one relationship. For example, use the @JoinColumn annotation in your SomeData class:

// ... your annotations ...
public class SomeData {

    // ... your other fields ...

    @OneToOne
    @JoinColumn(name = "some_data_id", referencedColumnName = "id")
    private User user;

}

Here are some alternatives that you could use: https://www.baeldung.com/jpa-one-to-one