Use named selection for projections to avoid AliasCollisionException.

We now use explicitly named selection items when selecting items from a projection selection to avoid name clashes through implicit naming.

Signed-off-by: oualid.bouh <oualid.bouh@kleegroup.com>
Closes #4135
Original pull request: #4136

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

@@ -69,6 +69,7 @@ import org.springframework.util.Assert;
  * @author Greg Turnquist
  * @author Christoph Strobl
  * @author Jinmyeong Kim
+ * @author Oualid Bouh
  */
 public class JpaQueryCreator extends AbstractQueryCreator<String, JpqlQueryBuilder.Predicate>
 		implements JpqlQueryCreator {
@@ -299,7 +300,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<String, JpqlQueryBuild
 			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));
+						PropertyPath.from(selection, returnedType.getDomainType()), true).as(selection));
 			}
 
 			JpqlQueryBuilder.Expression distance = null;

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

@@ -65,6 +65,7 @@ import org.springframework.data.util.Lazy;
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Oualid Bouh
  */
 class JpaQueryCreatorTests {
 
@@ -76,6 +77,9 @@ class JpaQueryCreatorTests {
 
 	static List<JpqlQueryTemplates> ignoreCaseTemplates = List.of(JpqlQueryTemplates.LOWER, JpqlQueryTemplates.UPPER);
 
+	private static final TestMetaModel ORDER_WITH_RELATIONS = TestMetaModel.hibernateModel(
+			OrderWithRelations.class, Customer.class, Supplier.class);
+
 	@Test // GH-3588
 	void simpleProperty() {
 
@@ -1131,4 +1135,45 @@ class JpaQueryCreatorTests {
 			return queryCreator(partTree, returnedType, metamodel, queryTemplates, parameterAccessor.get());
 		}
 	}
+
+	@Test // GH-4135
+	void interfaceProjectionWithMultipleJoinsShouldGenerateUniqueAliases() {
+
+		queryCreator(ORDER_WITH_RELATIONS)
+				.forTree(OrderWithRelations.class, "findProjectionById")
+				.returning(OrderSummaryProjection.class)
+				.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",
+						DefaultJpaEntityMetadata.unqualify(OrderWithRelations.class))
+				.validateQuery();
+	}
+
+	@jakarta.persistence.Entity
+	static class OrderWithRelations {
+		@Id Long id;
+		@ManyToOne Customer customer;
+		@ManyToOne Supplier supplier;
+	}
+
+	@jakarta.persistence.Entity
+	static class Customer {
+		@Id Long id;
+		String name;
+	}
+
+	@jakarta.persistence.Entity
+	static class Supplier {
+		@Id Long id;
+		String name;
+	}
+
+	interface OrderSummaryProjection {
+		Long getId();
+		Long getCustomerId();      // → customer.id
+		Long getSupplierId();      // → supplier.id
+		String getCustomerName();  // → customer.name
+		String getSupplierName();  // → supplier.name
+	}
 }