spring-data-commons Improve Querydsl support in custom repositories [DATACMNS-898]

Andrei Ivanov opened DATACMNS-898 and commented

Hi, As far as I understand from the documentation, working with Querydsl in a repository means that the repository interface should extend QueryDslPredicateExecutor:

public interface SiteAccessRequestsRepository extends PagingAndSortingRepository<SiteAccessRequest, Long>, QueryDslPredicateExecutor<SiteAccessRequest> {
}

This seems a bit weird to me because now the "query" gets created in the service/facade layer:

import com.example.siteaccess.dao.expressions.SiteAccessRequestExpressions;
@Service
public class SiteAccessRequestsFacadeImpl implements SiteAccessRequestsFacade {

	@Override
	public Page<SiteAccessRequest> getSiteAccessRequests(SiteAccessRequest probe, Pageable pageable) throws BusinessException {
		Predicate predicate = SiteAccessRequestExpressions.byExample(probe);
		return siteAccessRequestsRepository.findAll(predicate, pageable);
	}
}

And this also make integration testing difficult, as this is similar to having a method like findAll(String sql) defined in the repository interface.

So I tried to create a custom repository for this:

interface SiteAccessRequestsRepositoryCustom {
	Page<SiteAccessRequest> findByExample(SiteAccessRequest probe, Pageable pageable);
}

public class SiteAccessRequestsRepositoryImpl extends QueryDslRepositorySupport implements SiteAccessRequestsRepositoryCustom {

	public SiteAccessRequestsRepositoryImpl() {
		super(SiteAccessRequest.class);
	}

	@Override
	public Page<SiteAccessRequest> findByExample(SiteAccessRequest criteria, Pageable pageable) {
		Predicate predicate = SiteAccessRequestExpressions.byExample(criteria);
		//JPQLQuery<?> countQuery = createQuery(predicate);

		return null;
	}
}

This is were I got stuck. When using the QueryDslPredicateExecutor, the findAll(Predicate predicate, Pageable pageable) method is handled by QueryDslJpaRepository. But QueryDslRepositorySupport has only some basic methods to perform queries. What I am suggesting is to move some of the methods from QueryDslJpaRepository to QueryDslPredicateExecutor to make this case easier to implement.

Or maybe there already is a better way to implement custom repositories with Querydsl that I haven't seen?

Affects: 1.12.2 (Hopper SR2)