Unique column fails PUT request for nested collections [DATAREST-1544]

Lexanius opened DATAREST-1544 and commented

Hi, 

tanks for spring data. But now i have a bug.

I have a two Entities Station and Point. Point is a not exported embedded class in Station with a OneToMany relation. For both exists a @RepositoryRestResource Repository with the point one is exported = false. The Entity Point has a unique field name. Both Entities have exposed ids. The application use application/json as default MediaType.

If i want to update via PUT the Station and the points by removing the first element of the REST request, i get a Unique index or primary key violation for name.

E.g:
Existing data (in the database):

Station A {id: 1, points: [{id: 1, name: 'a'}, {id: 2, name: 'b'}, {id: 3, name: 'c'}]`

• (0) Should replace with

Station A {id: 1, points: [{id: 1, name: 'a'}, {id: 2, name: 'b'}]

* (1) Should replace with ```
Station A {id: 1, points: [{id: 2, name: 'b'}, {id: 3, name: 'c'}]
``` *not work*.

(1) is transformed to ```
Station A {id: 1, points: [{id: 1, name: 'b'}, {id: 2, name: 'c'}] 
``` with 2 database executes _updates _and a _delete _ (in this order).
So that the database has the state before the _delete_: ```
Station A {id: 1, points: [{id: 1, name: 'b'}, {id: 2, name: 'c'}, {id: 3, name: 'c'}]
```. This cause the `_Unique index or primary key violation_`.

It should be ```
Station A {id: 1, points: [{id: 2, name: 'b'}, {id: 3, name: 'c'}]

I try to batch the request but this wont help, if i use patch the application thows a exception because of the id changing. I think the changing is done in the method DomainObjectReader#mergeCollections.

Removing the unique fields helps, but this is not a solution. What should i do? Is there a option to prevent the id changes?

Code-snippets:

@Entity
@JsonIgnoreProperties(value = \{"new"})
public class Station extends AbstractPersistable<Long> {

 @NotNull
 private String name;

 @JsonManagedReference("point")
 @OneToMany(mappedBy = "station", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
 @NotNull
 private List<Point> points = new ArrayList<>();

}

&mdash;

@Entity
@JsonIgnoreProperties(value = { "new" })
public class Point extends AbstractPersistable<Long>{

    @ManyToOne
    @JoinColumn(name = "STATION_ID", referencedColumnName = "ID", nullable = false, updatable = false)
    @JsonBackReference("point")
    @RestResource(exported = false)
    privateStation station;

    @NotEmpty
    @Column(unique = true)
    private String name;
}

&mdash;

@RepositoryRestResource(collectionResourceRel = "results", path = "station")
public interface StationRepository extends JpaRepository<Station, Long> {}

&mdash;

@RepositoryRestResource(exported = false, collectionResourceRel = "results", path = "point")
public interface PointRepository extends JpaRepository<Point, Long> {}

&mdash;

@Configuration
public class RestConfiguration implements RepositoryRestConfigurer {

    @Autowired
    private EntityManager entityManager;

    @Override
    public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
        config.setDefaultMediaType(MediaType.APPLICATION_JSON);
        config.exposeIdsFor(entityManager.getMetamodel().getEntities().stream()
            .map(Type::getJavaType)
            .toArray(Class[]::new));
    }
}

Affects: 3.3.1 (Neumann SR1)