DATAJPA-1080 - Use From instead of Root to sort Join

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

@@ -70,6 +70,7 @@ import org.springframework.util.StringUtils;
  * @author Komi Innocent
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Sébastien Péralta
  */
 public abstract class QueryUtils {
 
@@ -478,11 +479,11 @@ public abstract class QueryUtils {
 	 * Turns the given {@link Sort} into {@link javax.persistence.criteria.Order}s.
 	 * 
 	 * @param sort the {@link Sort} instance to be transformed into JPA {@link javax.persistence.criteria.Order}s.
-	 * @param root must not be {@literal null}.
+	 * @param from must not be {@literal null}.
 	 * @param cb must not be {@literal null}.
 	 * @return
 	 */
-	public static List<javax.persistence.criteria.Order> toOrders(Sort sort, Root<?> root, CriteriaBuilder cb) {
+	public static List<javax.persistence.criteria.Order> toOrders(Sort sort, From<?,?> from, CriteriaBuilder cb) {
 
 		List<javax.persistence.criteria.Order> orders = new ArrayList<javax.persistence.criteria.Order>();
 
@@ -490,11 +491,11 @@ public abstract class QueryUtils {
 			return orders;
 		}
 
-		Assert.notNull(root, "Root must not be null!");
+		Assert.notNull(from, "From must not be null!");
 		Assert.notNull(cb, "CriteriaBuilder must not be null!");
 
 		for (org.springframework.data.domain.Sort.Order order : sort) {
-			orders.add(toJpaOrder(order, root, cb));
+			orders.add(toJpaOrder(order, from, cb));
 		}
 
 		return orders;
@@ -533,15 +534,15 @@ public abstract class QueryUtils {
 	 * Creates a criteria API {@link javax.persistence.criteria.Order} from the given {@link Order}.
 	 * 
 	 * @param order the order to transform into a JPA {@link javax.persistence.criteria.Order}
-	 * @param root the {@link Root} the {@link Order} expression is based on
+	 * @param from the {@link From} the {@link Order} expression is based on
 	 * @param cb the {@link CriteriaBuilder} to build the {@link javax.persistence.criteria.Order} with
 	 * @return
 	 */
 	@SuppressWarnings("unchecked")
-	private static javax.persistence.criteria.Order toJpaOrder(Order order, Root<?> root, CriteriaBuilder cb) {
+	private static javax.persistence.criteria.Order toJpaOrder(Order order, From<?,?> from, CriteriaBuilder cb) {
 
-		PropertyPath property = PropertyPath.from(order.getProperty(), root.getJavaType());
-		Expression<?> expression = toExpressionRecursively(root, property);
+		PropertyPath property = PropertyPath.from(order.getProperty(), from.getJavaType());
+		Expression<?> expression = toExpressionRecursively(from, property);
 
 		if (order.isIgnoreCase() && String.class.equals(expression.getJavaType())) {
 			Expression<String> lower = cb.lower((Expression<String>) expression);

src/test/java/org/springframework/data/jpa/repository/query/QueryUtilsIntegrationTests.java

@@ -33,6 +33,7 @@ import javax.persistence.Persistence;
 import javax.persistence.PersistenceContext;
 import javax.persistence.criteria.CriteriaBuilder;
 import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Join;
 import javax.persistence.criteria.JoinType;
 import javax.persistence.criteria.Root;
 import javax.persistence.spi.PersistenceProvider;
@@ -42,6 +43,8 @@ import javax.persistence.spi.PersistenceProviderResolverHolder;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mockito;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.jpa.domain.sample.Category;
 import org.springframework.data.jpa.domain.sample.Order;
 import org.springframework.data.jpa.domain.sample.User;
@@ -54,6 +57,7 @@ import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
  * Integration tests for {@link QueryUtils}.
  * 
  * @author Oliver Gierke
+ * @author Sébastien Péralta
  */
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration("classpath:infrastructure.xml")
@@ -151,6 +155,20 @@ public class QueryUtilsIntegrationTests {
 		verify(mock, times(0)).join(Mockito.eq("product"), Mockito.any(JoinType.class));
 	}
 
+	@Test // DATAJPA-1080
+	public void sortByJoinColumn() {
+		CriteriaBuilder builder = em.getCriteriaBuilder();
+		CriteriaQuery<User> query = builder.createQuery(User.class);
+		Root<User> root = query.from(User.class);
+		Join<User, User> join = root.join("manager", JoinType.LEFT);
+
+		Sort sort = new Sort(Direction.ASC, "age");
+
+		List<javax.persistence.criteria.Order> orders = QueryUtils.toOrders(sort, join, builder);
+
+		assertThat(orders, hasSize(1));
+	}
+
 	@Entity
 	static class Merchant {