DATAJPA-456 - Add support for specifying only the projection part of a custom count query.

We now support to specify just the projection part for the count query generation via the "countProjection" property of the @Query annotation.
This avoids having to repetitively specify parts of the original query.

Original pull request: #84.

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

@@ -1393,6 +1393,34 @@ public class UserRepositoryTests {
 		assertThat(result, is(data));
 	}
 
+	/**
+	 * @see DATAJPA-456
+	 */
+	@Test
+	public void findPaginatedExplicitQueryWithCountQueryProjection() {
+
+		firstUser.setFirstname(null);
+
+		flushTestUsers();
+
+		Page<User> result = repository.findAllByFirstnameLike("", new PageRequest(0, 10));
+
+		assertThat(result.getContent().size(), is(3));
+	}
+
+	/**
+	 * @see DATAJPA-456
+	 */
+	@Test
+	public void findPaginatedNamedQueryWithCountQueryProjection() {
+
+		flushTestUsers();
+
+		Page<User> result = repository.findByNamedQueryAndCountProjection("Gierke", new PageRequest(0, 10));
+
+		assertThat(result.getContent().size(), is(1));
+	}
+
 	private Page<User> executeSpecWithSort(Sort sort) {
 
 		flushTestUsers();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2013 the original author or authors.
+ * Copyright 2008-2014 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.
@@ -272,6 +272,15 @@ public class QueryUtilsUnitTests {
 		assertCountQuery("select p.lastname,p.firstname from Person p", "select count(p) from Person p");
 	}
 
+	/**
+	 * @see DATAJPA-456
+	 */
+	@Test
+	public void createCountQueryFromTheGivenCountProjection() {
+		assertThat(createCountQueryFor("select p.lastname,p.firstname from Person p", "p.lastname"),
+				is("select count(p.lastname) from Person p"));
+	}
+
 	private void assertCountQuery(String originalQuery, String countQuery) {
 		assertThat(createCountQueryFor(originalQuery), is(countQuery));
 	}

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

@@ -368,4 +368,16 @@ public interface UserRepository extends JpaRepository<User, Integer>, JpaSpecifi
 	 */
 	@Procedure
 	Integer plus1(@Param("arg") Integer arg);
+
+	/**
+	 * @see DATAJPA-456
+	 */
+	@Query(value = "select u from User u where u.firstname like ?1%", countProjection = "u.firstname")
+	Page<User> findAllByFirstnameLike(String firstname, Pageable page);
+
+	/**
+	 * @see DATAJPA-456
+	 */
+	@Query(name = "User.findBySpringDataNamedQuery", countProjection = "u.firstname")
+	Page<User> findByNamedQueryAndCountProjection(String firstname, Pageable page);
 }