From e1df922bbcdd7ed4eb3bc87437158bb40cddb3d6 Mon Sep 17 00:00:00 2001
From: Jens Schauder <jschauder@vmware.com>
Date: Fri, 3 Dec 2021 11:27:11 +0100
Subject: [PATCH] Correctly handle exists when it should return false.

In the previous implementation it would throw an exception.

Original pull request #2368
---
 .../repository/support/SimpleJpaRepository.java    |  7 ++++---
 .../data/jpa/repository/UserRepositoryTests.java   | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java b/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java
index 75ed0f491..231a50813 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java
@@ -75,8 +75,8 @@ import org.springframework.util.Assert;
  * @author Moritz Becker
  * @author Sander Krabbenborg
  * @author Jesse Wouters
- * @param <T> the type of the entity to handle
- * @param <ID> the type of the entity's identifier
+ * @author Greg Turnquist
+ * @author Yanming Zhou
  */
 @Repository
 @Transactional(readOnly = true)
@@ -527,12 +527,13 @@ public class SimpleJpaRepository<T, ID> implements JpaRepositoryImplementation<T
 	 */
 	@Override
 	public <S extends T> boolean exists(Example<S> example) {
+
 		Specification<S> spec = new ExampleSpecification<>(example, this.escapeCharacter);
 		CriteriaQuery<Integer> cq = this.em.getCriteriaBuilder().createQuery(Integer.class);
 		cq.select(this.em.getCriteriaBuilder().literal(1));
 		applySpecificationToCriteria(spec, example.getProbeType(), cq);
 		TypedQuery<Integer> query = applyRepositoryMethodMetadata(this.em.createQuery(cq));
-		return query.setMaxResults(1).getSingleResult() != null;
+		return query.setMaxResults(1).getResultList().size() == 1;
 	}
 
 	/*
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 ce28bbfd3..e0173f3e0 100644
--- a/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
@@ -2058,6 +2058,20 @@ public class UserRepositoryTests {
 		assertThat(exists).isEqualTo(true);
 	}
 
+	@Test // GH-2368
+	void existsByExampleNegative() {
+
+		flushTestUsers();
+
+		User prototype = new User();
+		prototype.setAge(4711); // there is none with that age
+
+		Example<User> example = Example.of(prototype, matching().withIgnorePaths("createdAt"));
+		boolean exists = repository.exists(example);
+
+		assertThat(exists).isEqualTo(false);
+	}
+
 	@Test // DATAJPA-905
 	void executesPagedSpecificationSettingAnOrder() {