[SOLVED] Spring Data: Query DTOs with QueryDSL predicates

Spring Data: Query DTOs with QueryDSL predicates

I am using QueryDSL to query/filter entities (Document):

   public interface DocumentRepository extends PagingAndSortingRepository<Document, Long>, QueryDslPredicateExecutor<Document>

Then I build QueryDSL Predicates and use method findAll to filter results:

   Predicate predicate = myBuilder.buildPredicate(myUserFilterObject)
   Page<Document> page = documentRepository.findAll(predicate, pageable)

It works well except for that I need to avoid N+1 selects (JPA). Is there any way to query DTOs instead of entities (but still use QueryDSL predicates) or is it possible to apply EntityGraphs here (didn't work for me)?

Solution

From Spring Data JPA 2.1 onwards you can use @EntityGraph annotation.

public interface DocumentRepository extends PagingAndSortingRepository<Document, Long>, QueryDslPredicateExecutor<Document> {
    @EntityGraph(attributePaths = { "name_of_collection_to_load" })
    Page<Document> findAll(com.querydsl.core.types.Predicate predicate, Pageable pageable)
}