From 26a51e52102af0da1bf2e87c657325ecce6817d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Hu=CC=88gelmeyer?= <p.huegelmeyer@gmail.com>
Date: Wed, 6 Jun 2012 15:00:18 +0200
Subject: [PATCH] #1 - Avoid lookup of entities if no revision numbers found.

We now eagerly return an empty Revisions instance in case we don't
find revision numbers for an entity with a given ID. Not doing so
caused issues with database vendors as they might expect at least a
single revision number.
---
 .../repository/support/EnversRevisionRepositoryImpl.java   | 3 ++-
 .../repository/support/RepositoryIntegrationTest.java      | 7 ++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/springframework/data/envers/repository/support/EnversRevisionRepositoryImpl.java b/src/main/java/org/springframework/data/envers/repository/support/EnversRevisionRepositoryImpl.java
index b75dc92..70a250b 100755
--- a/src/main/java/org/springframework/data/envers/repository/support/EnversRevisionRepositoryImpl.java
+++ b/src/main/java/org/springframework/data/envers/repository/support/EnversRevisionRepositoryImpl.java
@@ -114,7 +114,8 @@ public class EnversRevisionRepositoryImpl<T, ID extends Serializable, N extends
 		AuditReader reader = AuditReaderFactory.get(entityManager);
 		List<? extends Number> revisionNumbers = reader.getRevisions(type, id);
 
-		return getEntitiesForRevisions((List<N>) revisionNumbers, id, reader);
+		return revisionNumbers.isEmpty() ? new Revisions<N, T>(Collections.EMPTY_LIST) : getEntitiesForRevisions(
+				(List<N>) revisionNumbers, id, reader);
 	}
 
 	/*
diff --git a/src/test/java/org/springframework/data/envers/repository/support/RepositoryIntegrationTest.java b/src/test/java/org/springframework/data/envers/repository/support/RepositoryIntegrationTest.java
index 36257fe..1299b1e 100755
--- a/src/test/java/org/springframework/data/envers/repository/support/RepositoryIntegrationTest.java
+++ b/src/test/java/org/springframework/data/envers/repository/support/RepositoryIntegrationTest.java
@@ -15,7 +15,7 @@
  */
 package org.springframework.data.envers.repository.support;
 
-import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
 import java.util.Arrays;
@@ -102,4 +102,9 @@ public class RepositoryIntegrationTest {
 		Revisions<Integer, License> wrapper = new Revisions<Integer, License>(revisions.getContent());
 		assertThat(wrapper.getLatestRevision(), is(revision));
 	}
+
+	@Test
+	public void returnsEmptyRevisionsForUnrevisionedEntity() {
+		assertThat(countryRepository.findRevisions(100L).getContent(), is(hasSize(0)));
+	}
 }