DATACMNS-566 - Allow sorting by QueryDsl operator expressions.

Previously we only allowed to sort by QueryDsl path expressions. With this change we now also support ordering by operator expressions, e.g. yearMonth() on a date property.

Original pull request: #94.

Author: Thomas Darimont

src/main/java/org/springframework/data/querydsl/QSort.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 the original author or authors.
+ * Copyright 2013-2014 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.
@@ -25,6 +25,7 @@
 
 import com.mysema.query.types.Expression;
 import com.mysema.query.types.OrderSpecifier;
+import com.mysema.query.types.Path;
 
 /**
  * Sort option for queries that wraps a querydsl {@link OrderSpecifier}.
@@ -86,7 +87,8 @@ private static Order toOrder(OrderSpecifier<?> orderSpecifier) {
 		Assert.notNull(orderSpecifier, "Order specifier must not be null!");
 
 		Expression<?> target = orderSpecifier.getTarget();
-		Object targetElement = ((com.mysema.query.types.Path<?>) target).getMetadata().getElement();
+		Object targetElement = target instanceof Path ? ((com.mysema.query.types.Path<?>) target).getMetadata()
+				.getElement() : target;
 
 		Assert.notNull(targetElement, "Target element must not be null!");
 

src/test/java/org/springframework/data/querydsl/QSortUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 the original author or authors.
+ * Copyright 2013-2014 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.
@@ -15,8 +15,9 @@
  */
 package org.springframework.data.querydsl;
 
-import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
+import static org.hamcrest.Matchers.hasItems;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
 
 import java.util.List;
 
@@ -146,4 +147,18 @@ public void concatenatesPlainSortCorrectly() {
 		assertThat(result, is(Matchers.<Order> iterableWithSize(2)));
 		assertThat(result, hasItems(new Order(Direction.ASC, "lastname"), new Order(Direction.ASC, "firstname")));
 	}
+	
+	/**
+	 * @see DATACMNS-566
+	 */
+	@Test
+	public void shouldSupportSortByOperatorExpressions() {
+
+		QUser user = QUser.user;
+		QSort sort = new QSort(user.dateOfBirth.yearMonth().asc());
+
+		Sort result = sort.and(new Sort(Direction.ASC, "lastname"));
+		assertThat(result, is(Matchers.<Order> iterableWithSize(2)));
+		assertThat(result, hasItems(new Order(Direction.ASC, "lastname"), new Order(Direction.ASC, user.dateOfBirth.yearMonth().toString())));
+	}
 }

src/test/java/org/springframework/data/querydsl/User.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2013 the original author or authors.
+ * Copyright 2011-2014 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.
@@ -15,6 +15,8 @@
  */
 package org.springframework.data.querydsl;
 
+import java.util.Date;
+
 import com.mysema.query.annotations.QueryEntity;
 
 /**
@@ -25,4 +27,5 @@
 public class User {
 	String firstname;
 	String lastname;
+	Date dateOfBirth;
 }