SpringDataJPA: custom data mapping with Native Query

Question

public interface UserRepository extends JpaRepository<User, Long> {

  @Query(value = "SELECT * FROM USERS WHERE EMAIL_ADDRESS = ?0", nativeQuery = true)
  User findByEmailAddress(String emailAddress);
}

Let's say I have the code above where I select * from user. What should I do if I don't want this method to return User object. Is there a way I can manually map the data to a custom object MyUser? Can I do all this in the UserRepository interface?

Thanks!

Answer 1

What about interface based projection?

Basically you write interface with getters that correspond to SQL query parameters.

In this way you even don't need to force @Id parameter on projection:

@Entity
public class Book {
     @Id
     private Long id;
     private String title;
     private LocalDate published;
}

public interface BookReportItem {
     int getYear();
     int getMonth();
     long getCount();
}

public interface BookRepository extends Repository<Book, Long> {
     @Query(value = "select " +
                    "  year(b.published) as year," +
                    "  month(b.published) as month," +
                    "  count(b) as count," +
                    " from Book b" +
                    " group by year(b.published), month(b.published)")
     List<BookReportItem> getPerMonthReport();
}

It uses org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap underneath as proxy for interface in current Spring implementation.

It works for nativeQuery = true too.

Answer 2

You can do something like this

@Query(value = "SELECT YOUR Column1, ColumnN FROM USERS WHERE EMAIL_ADDRESS = ?0", nativeQuery = true)
List<Object[]> findByEmailAddress(String emailAddress);

You have to do the mapping. Take a look at the Spring Data Repository as well. Source