Entity cache key is built differently on read than on write

lib/Doctrine/ORM/Cache/DefaultQueryCache.php

@@ -111,10 +111,11 @@ public function get(QueryCacheKey $key, ResultSetMapping $rsm, array $hints = ar
         $region      = $persister->getCacheRegion();
         $regionName  = $region->getName();
 
+        $cm = $this->em->getClassMetadata($entityName);
         // @TODO - move to cache hydration component
         foreach ($entry->result as $index => $entry) {
 
-            if (($entityEntry = $region->get($entityKey = new EntityCacheKey($entityName, $entry['identifier']))) === null) {
+            if (($entityEntry = $region->get($entityKey = new EntityCacheKey($cm->rootEntityName, $entry['identifier']))) === null) {
 
                 if ($this->cacheLogger !== null) {
                     $this->cacheLogger->entityCacheMiss($regionName, $entityKey);

tests/Doctrine/Tests/Models/Cache/Attraction.php

@@ -5,7 +5,7 @@
 use Doctrine\Common\Collections\ArrayCollection;
 
 /**
- * @Cache
+ * @Cache("NONSTRICT_READ_WRITE")
  * @Entity
  * @Table("cache_attraction")
  * @InheritanceType("SINGLE_TABLE")

tests/Doctrine/Tests/ORM/Functional/Ticket/DDC4003Test.php

@@ -0,0 +1,60 @@
+<?php namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\ORM\Cache\Persister\CachedPersister;
+use Doctrine\Tests\Models\Cache\Bar;
+use Doctrine\Tests\ORM\Functional\SecondLevelCacheAbstractTest;
+
+class DDC4003Test extends SecondLevelCacheAbstractTest
+{
+    public function test_reads_through_repository_same_data_that_it_wrote_in_cache()
+    {
+        $this->loadFixturesCountries();
+        $this->loadFixturesStates();
+        $this->loadFixturesCities();
+        $this->loadFixturesAttractions();
+
+        // Get the id of the first bar
+        $id = $this->attractions[0]->getId();
+
+        $repository = $this->_em->getRepository(Bar::CLASSNAME);
+
+        /**
+         * This instance is fresh new, no QueryCache, so the full entity gets loaded from DB.
+         * It will be saved in the WRONG KEY (notice the cache.bar at the end):
+         * doctrine_tests_models_cache_attraction[doctrine_tests_models_cache_attraction_doctrine.tests.models.cache.bar_1][1]
+         *
+         * @var Bar $bar
+         */
+        $bar = $repository->findOneBy(['id' => $id]);
+
+        // Let's change it so that we can compare its state
+        $bar->setName($newName = uniqid());
+        $this->_em->persist($bar);
+        $this->_em->flush();
+
+        /**
+         * Flush did 2 important things for us:
+         * 1: saved the entity in its right key (notice the cache.attraction at the end):
+         *     doctrine_tests_models_cache_attraction[doctrine_tests_models_cache_attraction_doctrine.tests.models.cache.attraction_1][1]
+         * 2: Updated the TimestampRegion cache, so that the QueryCache is actually discarded.
+         *
+         * So, first findOneBy will hit DB, and its entity will not be loaded from cache.
+         */
+        $repository->findOneBy(['id' => $id]);
+
+        // Lets clear EM so that we don't hit IdentityMap at all.
+        $this->_em->clear();
+
+        /**
+         * Here's the failing step:
+         * Right now QueryCache will HIT, as nothing changed between the last one and now.
+         * QueryCache holds a reference to the WRONG KEY, as we saw was formed in line 24 of this test.
+         * So this instance won't be updated and will have the original name ("Boteco São Bento"), and not the uniqid().
+         *
+         * @var Bar $cached
+         */
+        $cached = $repository->findOneBy(['id' => $id]);
+
+        $this->assertEquals($newName, $cached->getName());
+    }
+}