[DELTASPIKE-699] Signature relaxing of attribute method() in CriteriaSupport

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.0
• Fix Version/s: 1.0.3
• Component/s: Data-Module
• Assignee: Thomas Hug
• Reporter: Radu Creanga
• Created: 26/Aug/14 10:56
• Updated: 24/Sep/14 22:10
• Resolved: 09/Sep/14 09:43

Description

Suppose one has an entity class hierarchy, such as when moving auditing fields into a mapped superclass.

@MappedSuperclass
@EntityListeners(AuditEntityListener.class)
public abstract class Auditable implements Serializable

{ @CreatedOn @Temporal(TemporalType.TIMESTAMP) private Date created; @ModifiedOn @Temporal(TemporalType.TIMESTAMP) private Date modified; // getters, setters }

@Entity
public class Item extends Auditable

{ @Id private Long id; @Basic private String name; // getters, setters }

Then an metamodel processor would generate the following metamodel classes:

@StaticMetamodel(Auditable.class)
public abstract class Auditable_

{ public static volatile SingularAttribute<Auditable, Date> created; public static volatile SingularAttribute<Auditable, Date> modified; }

@StaticMetamodel(Item.class)
public abstract class Item_ extends com.mobilabsolutions.nappkin.web.dto.Auditable_

{ public static volatile SingularAttribute<Item, Long> id; public static volatile SingularAttribute<Item, String> name; }

For the sake of completeness, here's the repository declaration with criteria support:

@Repository
public interface ItemRepository extends EntityRepository<Item, Long>,
CriteriaSupport<Item> {

}

Then, if one wants to do the following:

@Inject
private ItemRepository itemRepository;

public void someMethod() {
this.itemRepository.criteria().select(
this.itemRepository.attribute(Item_.name),
this.itemRepository.attribute(Item_.modified));
}

the source won't compile, because the declaration of the attribute() method in CriteriaSupport:

public interface CriteriaSupport<E>
{
...

/**

• Create a query selection for an Entity attribute.
• @param attribute Attribute to show up in the result selection
• @return {@link QuerySelection}

  part of a

  {@link Criteria#select(Class, QuerySelection...)}

  call.
  */
  <X> QuerySelection<E, X> attribute(SingularAttribute<E, X> attribute);

...

}

Should change the method signature to:

<X> QuerySelection<E, X> attribute(SingularAttribute<? super E, X> attribute);

The mapped superclass doesn't have to have anything to do with auditing, but that's the example that came to mind.