Types with a @IdClass with a single attribute use the underlying @Id property type within repositories

[payne911]

Context

When my service calls repository.delete(myEntity), I get the following error:

105 | You have provided an instance of an incorrect PK class for this find operation. Class expected : class com.foo.PrimaryKey, Class received : class java.lang.String.

The repository interface extends CrudRepository<MyEntity, PrimaryKey>.

I use @IdClass(PrimaryKey.class) on my @Entity class and have labeled the relevant field with @Id. There is a single field in the PrimaryKey, and it's a String. We do this to keep our codebase consistent so that every @Entity always declares its primary key as a composite key (because many others do use a proper composite key).

Code

• Repository:

public interface MyEntityCRUDRepository extends CrudRepository<MyEntity, PrimaryKey> { }
public interface MyEntityCustomRepository { /* some custom operations */ }

@Repository
public interface MyEntityRepository extends MyEntityCRUDRepository, MyEntityCustomRepository { }

• Service:

@Service
@Transactional(rollbackFor = Exception.class)
@RequiredArgsConstructor
public class MyEntityService {
    private final MyEntityRepository repository;

    public void destroy(final PrimaryKey pk) {
//        repository.deleteById(pk); // also returns the error
        MyEntity myEntity = repository.findById(pk)
                .orElseThrow(() -> new IllegalArgumentException(DOES_NOT_EXIST));
        repository.delete(myEntity); // returns the error
    }
}

• JPA entity:

@Entity
@Table(name = "myentity")
@JsonIgnoreProperties(ignoreUnknown = true)
@Data
@NoArgsConstructor
@AllArgsConstructor
@IdClass(PrimaryKey.class)
public class MyEntity {

    @Id
    @Column(name = "the_id", updatable = false)
    private String theId;

    // other fields which aren't part of the primary key
}

• Primary key class:

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class PrimaryKey implements Serializable {
    private String theId;
}

Partial analysis (could be wrong)

For some reason, Spring Data JPA internally calls em.find(MyEntity.class, primaryKeyString) instead of building a PrimaryKey instance from that String and using it, hence the error.

The same error happens when I try to call repository.deleteById(correspondingPrimaryKeyInstance) instead.

Framework code

This is where it fails:

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

Line 197 in a31c39d

T existing = (T) em.find(type, entityInformation.getId(entity));

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformation.java

Line 162 in acf01b6

return (ID) entityWrapper.getPropertyValue(idMetadata.getSimpleIdAttribute().getName());

Somehow, it seems like the (ID) cast has picked up the wrong class to assign to the ID generic (I would assume that it should come from the declared generic of the CrudRepository).

Temporary fix

To temporarily fix the problem, I can remove the @IdClass annotation, and change from:

public interface MyEntityCRUDRepository extends CrudRepository<MyEntity, PrimaryKey> { }

to:

public interface MyEntityCRUDRepository extends CrudRepository<MyEntity, String> { }

but that is not ideal because we would rather have a consistent approach that uses @IdClass for all our @Entity classes throughout the codebase.

[mp911de]

Thanks for reporting the issue. That is indeed a bug on our side. The meta-model makes it a bit difficult to identify whether @IdClass is being used but we are able to fix the problem.

[mp911de]

Another workaround is to let your entities implement Persistable.

[payne911]

Thank you for the quick fix. :)

I added two comments to your commit. They are probably irrelevant: I'm unaware of Spring's code-style guidelines.