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

@@ -32,6 +32,7 @@ import javax.persistence.TupleElement;
 import javax.persistence.TypedQuery;
 
 import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.jpa.provider.HibernateUtils;
 import org.springframework.data.jpa.repository.EntityGraph;
 import org.springframework.data.jpa.repository.query.JpaQueryExecution.CollectionExecution;
 import org.springframework.data.jpa.repository.query.JpaQueryExecution.ModifyingExecution;
@@ -45,6 +46,7 @@ import org.springframework.data.repository.query.ParametersParameterAccessor;
 import org.springframework.data.repository.query.RepositoryQuery;
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
+import org.springframework.data.util.Version;
 import org.springframework.util.Assert;
 
 /**
@@ -57,6 +59,8 @@ import org.springframework.util.Assert;
  */
 public abstract class AbstractJpaQuery implements RepositoryQuery {
 
+	protected static final Version HIBERNATE_VERSION_SUPPORTING_TUPLES = new Version(5, 2, 11);
+
 	private final JpaQueryMethod method;
 	private final EntityManager em;
 	private final JpaMetamodel metamodel;
@@ -223,6 +227,22 @@ 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 Class<?> getTypeToRead() {
+
+		ResultProcessor resultFactory = getQueryMethod().getResultProcessor();
+		ReturnedType returnedType = resultFactory.getReturnedType();
+
+		return returnedType.isProjecting() && !getMetamodel().isJpaManaged(returnedType.getReturnedType()) //
+				? HibernateUtils.isVersionOrBetter(HIBERNATE_VERSION_SUPPORTING_TUPLES) ? Tuple.class : null //
+				: null;
+	}
+
 	/**
 	 * Creates a {@link Query} instance for the given values.
 	 * 

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

@@ -17,13 +17,10 @@ package org.springframework.data.jpa.repository.query;
 
 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;
 
@@ -134,11 +131,8 @@ abstract class AbstractStringBasedJpaQuery extends AbstractJpaQuery {
 			return em.createQuery(queryString);
 		}
 
-		ResultProcessor resultFactory = getQueryMethod().getResultProcessor();
-		ReturnedType returnedType = resultFactory.getReturnedType();
+		Class<?> typeToRead = getTypeToRead();
 
-		return returnedType.isProjecting() && !getMetamodel().isJpaManaged(returnedType.getReturnedType()) //
-				? em.createQuery(queryString, Tuple.class) //
-				: em.createQuery(queryString);
+		return typeToRead == null ? em.createQuery(queryString) : em.createQuery(queryString, typeToRead);
 	}
 }

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

@@ -21,7 +21,6 @@ import javax.persistence.TypedQuery;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import org.springframework.data.jpa.provider.QueryExtractor;
 import org.springframework.data.repository.query.Parameters;
 import org.springframework.data.repository.query.QueryCreationException;
@@ -139,7 +138,11 @@ final class NamedQuery extends AbstractJpaQuery {
 	@Override
 	protected Query doCreateQuery(Object[] values) {
 
-		Query query = getEntityManager().createNamedQuery(queryName);
+		EntityManager em = getEntityManager();
+
+		Class<?> typeToRead = getTypeToRead();
+		Query query = typeToRead == null ? em.createNamedQuery(queryName) : em.createNamedQuery(queryName, typeToRead);
+
 		return createBinder(values).bindAndPrepare(query);
 	}
 

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

@@ -25,7 +25,6 @@ import org.springframework.data.repository.query.Parameters;
 import org.springframework.data.repository.query.RepositoryQuery;
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
-import org.springframework.data.util.Version;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 
 /**
@@ -38,8 +37,6 @@ import org.springframework.expression.spel.standard.SpelExpressionParser;
  */
 final class NativeJpaQuery extends AbstractStringBasedJpaQuery {
 
-	private static final Version HIBERNATE_VERSION_SUPPORTING_TUPLES = new Version(5, 2, 11);
-
 	private final Class<?> resultType;
 
 	/**

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

@@ -34,6 +34,9 @@ import javax.persistence.ManyToOne;
 import javax.persistence.NamedAttributeNode;
 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;
@@ -75,7 +78,11 @@ 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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2014 the original author or authors.
+ * Copyright 2013-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.data.jpa.infrastructure;
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import javax.persistence.EntityManager;
@@ -86,6 +87,7 @@ public abstract class MetamodelIntegrationTests {
 	public void doesNotExposeAliasForTupleIfNoneDefined() {
 
 		User user = new User();
+
 		user.setFirstname("Dave");
 		user.setEmailAddress("email");
 
@@ -99,4 +101,32 @@ 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));
+
+		List<String> aliases = new ArrayList<String>(elements.size());
+
+		for (TupleElement<?> element : elements) {
+			aliases.add(element.getAlias());
+		}
+
+		assertThat(aliases, containsInAnyOrder("firstname", "lastname"));
+	}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,4 +39,9 @@ public class OpenJpaMetamodelIntegrationTests extends MetamodelIntegrationTests
 	@Ignore
 	@Override
 	public void doesNotExposeAliasForTupleIfNoneDefined() {}
+
+	@Ignore
+	@Test
+	@Override
+	public void returnsAliasesInTuple() {}
 }

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

@@ -98,4 +98,11 @@ public class EclipseLinkNamespaceUserRepositoryTests extends NamespaceUserReposi
 	 */
 	@Override
 	public void supportsProjectionsWithNativeQueriesAndCamelCaseProperty() {}
+
+	/**
+	 * TODO: Remove, once https://bugs.eclipse.org/bugs/show_bug.cgi?id=289141 is fixed.
+	 */
+	@Override
+	@Test
+	public void bindsNativeQueryResultsToProjectionByName() {}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2017 the original author or authors.
+ * Copyright 2008-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -2217,6 +2217,24 @@ public class UserRepositoryTests {
 		assertThat(emailAddress, is(user.getEmailAddress()));
 	}
 
+	@Test // DATAJPA-1273
+	public void bindsNativeQueryResultsToProjectionByName() {
+
+		Assume
+				.assumeTrue(getHibernateVersion().isGreaterThanOrEqualTo(HIBERNATE_VERSION_SUPPORTING_TUPLE_ON_NATIVE_QUERIES));
+
+		flushTestUsers();
+
+		List<NameOnly> result = repository.findByNamedQueryWithAliasInInvertedOrder();
+
+		assertThat(result, is(not(empty())));
+
+		NameOnly element = result.get(0);
+
+		assertThat(element.getFirstname(), is("Joachim"));
+		assertThat(element.getLastname(), is("Arrasz"));
+	}
+
 	private Page<User> executeSpecWithSort(Sort sort) {
 
 		flushTestUsers();

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

@@ -486,6 +486,9 @@ public interface UserRepository
 	EmailOnly findEmailOnlyByNativeQuery(Integer id);
 
 
+	// DATAJPA-1273
+	List<NameOnly> findByNamedQueryWithAliasInInvertedOrder();
+
 	interface RolesAndFirstname {
 
 		String getFirstname();