Avoid JPQL selection aliasing by default.

We now no longer apply an alias for property paths within the selection list unless required aliases when using tuple queries to materialize projections.

Also, we now add correctly the AS keyword between the selection and the alias to remain spec-compliant.

Closes #4167

Author: mp911de

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java

@@ -288,7 +288,8 @@ private JpqlQueryBuilder.Select doSelect(Sort sort) {
 
 		if (returnedType.needsCustomConstruction()) {
 
-			Collection<String> requiredSelection = null;
+			boolean tupleQuery = useTupleQuery();
+			Collection<String> requiredSelection;
 			if (returnedType.getReturnedType().getPackageName().startsWith("java.util")
 					|| returnedType.getReturnedType().getPackageName().startsWith("jakarta.persistence")) {
 				requiredSelection = metamodel.managedType(returnedType.getDomainType()).getAttributes().stream()
@@ -299,16 +300,17 @@ private JpqlQueryBuilder.Select doSelect(Sort sort) {
 
 			List<JpqlQueryBuilder.Expression> paths = new ArrayList<>(requiredSelection.size());
 			for (String selection : requiredSelection) {
-				paths.add(JpqlUtils.toExpressionRecursively(metamodel, entity, entityType,
-						PropertyPath.from(selection, returnedType.getDomainType()), true).as(selection));
+				JpqlQueryBuilder.PathExpression expression = JpqlUtils.toExpressionRecursively(metamodel, entity, entityType,
+						PropertyPath.from(selection, returnedType.getDomainType()), true);
+				paths.add(tupleQuery ? expression.as(selection) : expression);
 			}
 
 			JpqlQueryBuilder.Expression distance = null;
 			if (searchQuery) {
 				distance = getDistanceExpression();
 			}
 
-			if (useTupleQuery()) {
+			if (tupleQuery) {
 
 				if (searchQuery) {
 					paths.add((distance != null ? distance : JpqlQueryBuilder.literal(0)).as("distance"));

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpqlQueryBuilder.java

@@ -521,8 +521,17 @@ default Select select(JpqlQueryBuilder.PathExpression path) {
 
 	}
 
+	/**
+	 * Interface specifying a selection that can be rendered to {@code String}.
+	 */
 	public interface Selection {
 
+		/**
+		 * Render the selection given {@link RenderContext} to string.
+		 *
+		 * @param context
+		 * @return the rendered selection.
+		 */
 		String render(RenderContext context);
 
 	}
@@ -658,7 +667,7 @@ public String render(RenderContext context) {
 
 				builder.append(path.render(context));
 				if (!context.isConstructorContext() && path instanceof AliasedExpression ae) {
-					builder.append(" ").append(ae.getAlias());
+					builder.append(" AS ").append(ae.getAlias());
 				}
 			}
 
@@ -1541,7 +1550,7 @@ public String toString() {
 	 * @param onTheJoin whether the path should target the join itself instead of matching {@link PropertyPath}.
 	 */
 	record PathAndOrigin(PropertyPath path, Origin origin,
-			boolean onTheJoin) implements PathExpression, AliasedExpression {
+			boolean onTheJoin) implements PathExpression {
 
 		@Override
 		public PropertyPath getPropertyPath() {
@@ -1558,11 +1567,6 @@ public String render(RenderContext context) {
 			}
 		}
 
-		@Override
-		public String getAlias() {
-			return path().getSegment();
-		}
-
 	}
 
 	/**

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

@@ -186,11 +186,6 @@ public void modifyingUpdateNativeQueryWorksWithJSQLParser() {}
 	@Test
 	public void scrollByPredicateKeysetWithInterfaceProjection() {}
 
-	@Disabled("EclipseLink treats id as keyword")
-	@Override
-	@Test
-	public void executesDerivedExistsQuery() {}
-
 	@Disabled("Not spec-compliant")
 	@Override
 	@Test

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/EclipseLinkUserRepositoryFinderTests.java

@@ -28,14 +28,6 @@
 @ContextConfiguration("classpath:eclipselink-h2.xml")
 class EclipseLinkUserRepositoryFinderTests extends UserRepositoryFinderTests {
 
-	@Disabled
-	@Override
-	void executesNotInQueryCorrectly() {}
-
-	@Disabled
-	@Override
-	void executesInKeywordForPageCorrectly() {}
-
 	@Disabled
 	@Override
 	void shouldProjectWithKeysetScrolling() {}

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/JpaQueryCreatorTests.java

@@ -707,7 +707,7 @@ void interfaceProjection() {
 				.returning(InterfaceProductProjection.class) //
 				.withParameters("spring") //
 				.as(QueryCreatorTester::create) //
-				.expectJpql("SELECT p.name name, p.productType productType FROM %s p WHERE p.name = ?1",
+				.expectJpql("SELECT p.name AS name, p.productType AS productType FROM %s p WHERE p.name = ?1",
 						DefaultJpaEntityMetadata.unqualify(Product.class)) //
 				.validateQuery();
 	}
@@ -722,7 +722,7 @@ void tupleProjection(Class<?> resultType) {
 				.withParameters("chris") //
 				.as(QueryCreatorTester::create) //
 				.expectJpql(
-						"SELECT p.id id, p.emailAddress emailAddress, p.firstname firstname, p.lastname lastname FROM %s p WHERE p.firstname = ?1",
+						"SELECT p.id AS id, p.emailAddress AS emailAddress, p.firstname AS firstname, p.lastname AS lastname FROM %s p WHERE p.firstname = ?1",
 						DefaultJpaEntityMetadata.unqualify(Person.class)) //
 				.validateQuery();
 	}
@@ -747,7 +747,7 @@ void exists() {
 				.forTree(Person.class, "existsPersonByFirstname") //
 				.returning(Long.class).withParameters("chris") //
 				.as(QueryCreatorTester::create) //
-				.expectJpql("SELECT p.id id FROM %s p WHERE p.firstname = ?1", DefaultJpaEntityMetadata.unqualify(Person.class)) //
+				.expectJpql("SELECT p.id FROM %s p WHERE p.firstname = ?1", DefaultJpaEntityMetadata.unqualify(Person.class)) //
 				.validateQuery();
 	}
 
@@ -1142,7 +1142,7 @@ void interfaceProjectionShouldGenerateUniqueSelectionAliases() {
 				.withParameters(1L) //
 				.as(QueryCreatorTester::create) //
 				.expectJpql(
-						"SELECT o.id id, c.id customerId, s.id supplierId, c.name customerName, s.name supplierName FROM %s o LEFT JOIN o.customer c LEFT JOIN o.supplier s WHERE o.id = ?1",
+						"SELECT o.id AS id, c.id AS customerId, s.id AS supplierId, c.name AS customerName, s.name AS supplierName FROM %s o LEFT JOIN o.customer c LEFT JOIN o.supplier s WHERE o.id = ?1",
 						DefaultJpaEntityMetadata.unqualify(OrderWithRelations.class))
 				.validateQuery();
 	}