From 44e4f1289ce35b7e633cb7085ac72f640c88bb61 Mon Sep 17 00:00:00 2001
From: Oliver Gierke <info@olivergierke.de>
Date: Mon, 5 Sep 2011 12:05:02 +0200
Subject: [PATCH] DATAJPA-86 - Pagination over queries using group-by works
 correctly.

Added handling of count methods for queries using group by. In case the count query returns multiple results we use the number of results instead of failing. If the result contains one result we use this one.
---
 .../data/jpa/repository/query/JpaQueryExecution.java     | 5 ++++-
 .../data/jpa/repository/UserRepositoryTests.java         | 9 +++++++++
 .../data/jpa/repository/sample/UserRepository.java       | 3 +++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
index 33d362483..fcaf3e9a1 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
@@ -15,6 +15,8 @@
  */
 package org.springframework.data.jpa.repository.query;
 
+import java.util.List;
+
 import javax.persistence.EntityManager;
 import javax.persistence.NoResultException;
 import javax.persistence.Query;
@@ -94,7 +96,8 @@ public abstract class JpaQueryExecution {
 
 			// Execute query to compute total
 			Query projection = repositoryQuery.createCountQuery(values);
-			Long total = (Long) projection.getSingleResult();
+			List<Long> counts = projection.getResultList();
+			Long total = counts.size() == 1 ? counts.get(0) : counts.size();
 
 			Query query = repositoryQuery.createQuery(values);
 
diff --git a/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java b/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
index af579d7f9..c6471bd49 100644
--- a/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
@@ -725,6 +725,15 @@ public class UserRepositoryTests {
 		assertThat(result, hasItem(firstUser));
 	}
 
+	@Test
+	public void executesPaginationForGroupByQueryCorrectly() {
+
+		flushTestUsers();
+
+		Page<String> results = repository.findWithGroupBy(new PageRequest(0, 10));
+		assertThat(results.getTotalPages(), is(1));
+	}
+
 	private Page<User> executeSpecWithSort(Sort sort) {
 
 		flushTestUsers();
diff --git a/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java b/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java
index 0d04d43c9..9a36e7ed5 100644
--- a/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java
+++ b/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java
@@ -178,4 +178,7 @@ public interface UserRepository extends JpaRepository<User, Integer>, JpaSpecifi
 	List<User> findBySpringDataNamedQuery(String lastname);
 
 	Page<User> findByLastnameLike(Pageable pageable, String lastname);
+
+	@Query("select u.lastname from User u group by u.lastname")
+	Page<String> findWithGroupBy(Pageable pageable);
 }