Spring Data Transformers.aliasToBean(AgentRecordDTO.class)

Question

I want to use Hibernate Transformation with Spring Data.

I have an entity AgentRecord with attributes as

@Entity
public class AgentRecord extends AbstractEntity<Long> {
        @ManyToOne
        private User processedBy;

        private String description;

        private RecordType recordType;

        private AgentRecordStatus status;
}

I am following the practice of setting required attributes to a different DTO called AgentRecordDTO and return it to Client-side(gwt).

public class AgentRecordDTO implements IsSerializable {

    private long processedBy;

    private String description;

    private RecordType recordType;

    private AgentRecordStatus status;
}

Instead of fetching all attributes of an entity, I want to fetch few attributes and set them to AgentRecordDTO like that of new AgentRecordDTO() I can do in hql, BUT want to do with Spring Data Specification.

My AgentRepository is

public interface AgentRecordRepository extends CrudRepository<AgentRecord, Long>, JpaSpecificationExecutor<AgentRecord> {

}

My Transformation incomplete code looks like

public Page<AgentRecordDTO> getAgentRecords(final long userId) {
    SimplePageable page = new SimplePageable(1, 10); //my custom object
    Page<AgentRecord> pages = agentRecordRepository.findAll(new Specification<AgentRecord>() {

        @Override
        public Predicate toPredicate(Root<AgentRecord> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
            //Projection plus Transformers.aliasToBean(AgentRecordDTO) missing here
            Predicate predicate = cb.equal(root.get("processedBy").get("id"), userId);
            if (null != predicate) {
                predicate = cb.or(predicate, cb.equal(root.get("recordType"), RecordType.VERIFICATION_REQUEST));
                predicate = cb.or(predicate, cb.equal(root.get("recordType"), RecordType.VERIFICATION));
            }

            return predicate;
        }
    }, new PageRequest(page.getPage(), page.getSize(), new Sort(new Order(Direction.DESC, "id"))));
    return null;
}

Hibernate 3.2: Transformers for HQL and SQL dated 03 Jun 2008 was the brilliant post, but

I couldn't win over it in Spring Data Specification.

Answer 1

Not a direct answer, but a circumvention..

Whenever Spring Data repository did not match my requirements I resorted to going straight into Hibernate from the entitymanager instead.

e.g.

entityManager.unwrap(Session.class).
    createSQLQuery(SPECIAL_QUERY).
    setTimestamp("requestTime", time).
    setParameter("currency", String.valueOf(currency)).
    setResultTransformer(
        Transformers.aliasToBean(BookingSummary.class)
    ).list();

I had a few summaries, that needed left outer joins, so no way to map it back into entities.