DATAJPA-1273 - Improve projected named query execution to use Tuples.

NamedQuery now inspects the ReturnedType of the query method to potentially create a JPA Query instance typed to Tuple for projections onto non JPA managed types. This will cause Tuple instances being returned that allow binding to projection accessors by the aliases defined in the query instead of a plain Object array that will rely on the declaration order of the columns to be returned being in sync with the declaration order of the accessors in the projection interface.

Disabled integration tests for EclipseLink as it apparently doesn't support Tuple as result type properly. Added a standalone test case to showcase the issue.

src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java

@@ -20,6 +20,7 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -234,6 +235,22 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 		return method.applyHintsToCountQuery() ? applyHints(countQuery, method) : countQuery;
 	}
 
+	/**
+	 * Returns the type to be used when creating the JPA query.
+	 * 
+	 * @return
+	 * @since 2.0.5
+	 */
+	protected Optional<Class<?>> getTypeToRead() {
+
+		ResultProcessor resultFactory = getQueryMethod().getResultProcessor();
+		ReturnedType returnedType = resultFactory.getReturnedType();
+
+		return returnedType.isProjecting() && !getMetamodel().isJpaManaged(returnedType.getReturnedType())
+				? Optional.of(Tuple.class)
+				: Optional.empty();
+	}
+
 	/**
 	 * Creates a {@link Query} instance for the given values.
 	 *

src/main/java/org/springframework/data/jpa/repository/query/AbstractStringBasedJpaQuery.java

@@ -19,13 +19,10 @@ import static org.springframework.data.jpa.repository.query.QueryParameterSetter
 
 import javax.persistence.EntityManager;
 import javax.persistence.Query;
-import javax.persistence.Tuple;
 
 import org.springframework.data.repository.query.EvaluationContextProvider;
 import org.springframework.data.repository.query.ParameterAccessor;
 import org.springframework.data.repository.query.ParametersParameterAccessor;
-import org.springframework.data.repository.query.ResultProcessor;
-import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.util.Assert;
 
@@ -140,11 +137,8 @@ abstract class AbstractStringBasedJpaQuery extends AbstractJpaQuery {
 			return em.createQuery(queryString);
 		}
 
-		ResultProcessor resultFactory = getQueryMethod().getResultProcessor();
-		ReturnedType returnedType = resultFactory.getReturnedType();
-
-		return returnedType.isProjecting() && !getMetamodel().isJpaManaged(returnedType.getReturnedType())
-				? em.createQuery(queryString, Tuple.class)
-				: em.createQuery(queryString);
+		return getTypeToRead() //
+				.<Query> map(it -> em.createQuery(queryString, it)) //
+				.orElseGet(() -> em.createQuery(queryString));
 	}
 }

src/main/java/org/springframework/data/jpa/repository/query/NamedQuery.java

@@ -145,7 +145,12 @@ final class NamedQuery extends AbstractJpaQuery {
 	@Override
 	protected Query doCreateQuery(Object[] values) {
 
-		Query query = getEntityManager().createNamedQuery(queryName);
+		EntityManager em = getEntityManager();
+
+		Query query = getTypeToRead() //
+				.<Query> map(it -> em.createNamedQuery(queryName, it)) //
+				.orElseGet(() -> em.createNamedQuery(queryName));
+
 		return parameterBinder.get().bindAndPrepare(query, values);
 	}
 

src/test/java/org/springframework/data/jpa/domain/sample/User.java

@@ -37,6 +37,7 @@ import javax.persistence.NamedEntityGraph;
 import javax.persistence.NamedEntityGraphs;
 import javax.persistence.NamedNativeQueries;
 import javax.persistence.NamedNativeQuery;
+import javax.persistence.NamedQueries;
 import javax.persistence.NamedQuery;
 import javax.persistence.NamedStoredProcedureQueries;
 import javax.persistence.NamedStoredProcedureQuery;
@@ -80,7 +81,11 @@ import javax.persistence.TemporalType;
 										@NamedAttributeNode(value = "colleagues", subgraph = "User.colleaguesOfColleagues") }),
 						@NamedSubgraph(name = "User.colleaguesOfColleagues",
 								attributeNodes = { @NamedAttributeNode("roles"), }) }) })
-@NamedQuery(name = "User.findByEmailAddress", query = "SELECT u FROM User u WHERE u.emailAddress = ?1")
+@NamedQueries({ //
+		@NamedQuery(name = "User.findByEmailAddress", //
+				query = "SELECT u FROM User u WHERE u.emailAddress = ?1"), //
+		@NamedQuery(name = "User.findByNamedQueryWithAliasInInvertedOrder", //
+				query = "SELECT u.lastname AS lastname, u.firstname AS firstname FROM User u ORDER BY u.lastname ASC") })
 @NamedStoredProcedureQueries({ //
 		@NamedStoredProcedureQuery(name = "User.plus1", procedureName = "plus1inout",
 				parameters = { @StoredProcedureParameter(mode = ParameterMode.IN, name = "arg", type = Integer.class),

src/test/java/org/springframework/data/jpa/infrastructure/EclipseLinkMetamodelIntegrationTests.java

@@ -50,4 +50,12 @@ public class EclipseLinkMetamodelIntegrationTests extends MetamodelIntegrationTe
 	@Ignore
 	@Override
 	public void doesNotExposeAliasForTupleIfNoneDefined() {}
+
+	/**
+	 * TODO: Remove, once https://bugs.eclipse.org/bugs/show_bug.cgi?id=289141 is fixed.
+	 */
+	@Test
+	@Ignore
+	@Override
+	public void returnsAliasesInTuple() {}
 }

src/test/java/org/springframework/data/jpa/infrastructure/MetamodelIntegrationTests.java

@@ -15,8 +15,9 @@
  */
 package org.springframework.data.jpa.infrastructure;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertThat;
 
 import java.util.List;
 
@@ -86,6 +87,7 @@ public abstract class MetamodelIntegrationTests {
 	public void doesNotExposeAliasForTupleIfNoneDefined() {
 
 		User user = new User();
+
 		user.setFirstname("Dave");
 		user.setEmailAddress("email");
 
@@ -99,4 +101,25 @@ public abstract class MetamodelIntegrationTests {
 		assertThat(elements, hasSize(1));
 		assertThat(elements.get(0).getAlias(), is(nullValue()));
 	}
+
+	@Test
+	@Transactional
+	public void returnsAliasesInTuple() {
+
+		User user = new User();
+		user.setFirstname("Dave");
+		user.setLastname("Matthews");
+		user.setEmailAddress("email");
+
+		em.persist(user);
+
+		TypedQuery<Tuple> query = em.createQuery(
+				"SELECT u.lastname AS lastname, u.firstname AS firstname FROM User u ORDER BY u.lastname ASC", Tuple.class);
+
+		List<Tuple> resultList = query.getResultList();
+		List<TupleElement<?>> elements = resultList.get(0).getElements();
+
+		assertThat(elements).hasSize(2);
+		assertThat(elements).extracting(TupleElement::getAlias).contains("firstname", "lastname");
+	}
 }

src/test/java/org/springframework/data/jpa/repository/EclipseLinkNamespaceUserRepositoryTests.java

@@ -101,7 +101,13 @@ public class EclipseLinkNamespaceUserRepositoryTests extends NamespaceUserReposi
 	@Ignore
 	@Override
 	@Test // DATAJPA-1248
-	public void supportsProjectionsWithNativeQueriesAndCamelCaseProperty() {
-		super.supportsProjectionsWithNativeQueriesAndCamelCaseProperty();
-	}
+	public void supportsProjectionsWithNativeQueriesAndCamelCaseProperty() {}
+
+	/**
+	 * TODO: Remove, once https://bugs.eclipse.org/bugs/show_bug.cgi?id=289141 is fixed.
+	 */
+	@Ignore
+	@Override
+	@Test
+	public void bindsNativeQueryResultsToProjectionByName() {}
 }

src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -2160,6 +2160,19 @@ public class UserRepositoryTests {
 		softly.assertAll();
 	}
 
+	@Test // DATAJPA-1273
+	public void bindsNativeQueryResultsToProjectionByName() {
+
+		flushTestUsers();
+
+		List<NameOnly> result = repository.findByNamedQueryWithAliasInInvertedOrder();
+
+		assertThat(result).element(0).satisfies(it -> {
+			assertThat(it.getFirstname()).isEqualTo("Joachim");
+			assertThat(it.getLastname()).isEqualTo("Arrasz");
+		});
+	}
+
 	private Page<User> executeSpecWithSort(Sort sort) {
 
 		flushTestUsers();

src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java

@@ -536,6 +536,9 @@ public interface UserRepository
 	@Query(value = "SELECT firstname FROM SD_User ORDER BY UCASE(firstname)", countQuery = "SELECT count(*) FROM SD_User", nativeQuery = true)
 	Page<String> findByNativeQueryWithPageable(@Param("pageable") Pageable pageable);
 
+	// DATAJPA-1273
+	List<NameOnly> findByNamedQueryWithAliasInInvertedOrder();
+
 	interface RolesAndFirstname {
 
 		String getFirstname();