Skip joined entity creation for empty relation (#10889)

lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php

@@ -367,7 +367,11 @@ protected function hydrateRowData(array $row, array &$result)
                     $parentObject = $this->resultPointers[$parentAlias];
                 } else {
                     // Parent object of relation not found, mark as not-fetched again
-                    $element = $this->getEntity($data, $dqlAlias);
+                    if (isset($nonemptyComponents[$dqlAlias])) {
+                        $element = $this->getEntity($data, $dqlAlias);
+                    } else {
+                        $element = null;
+                    }
 
                     // Update result pointer and provide initial fetch data for parent
                     $this->resultPointers[$dqlAlias]               = $element;

tests/Doctrine/Tests/ORM/Functional/Ticket/GH10889Test.php

@@ -0,0 +1,108 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\ORM\Mapping as ORM;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+/**
+ * @see   https://github.com/doctrine/orm/issues/10889
+ *
+ * @group GH10889
+ */
+class GH10889Test extends OrmFunctionalTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->createSchemaForModels(
+            GH10889User::class,
+            GH10889Finger::class,
+            GH10889Hand::class
+        );
+    }
+
+    public function testIssue(): void
+    {
+        $user = new GH10889User();
+        $hand = new GH10889Hand($user, null);
+
+        $this->_em->persist($user);
+        $this->_em->persist($hand);
+        $this->_em->flush();
+        $this->_em->clear();
+
+        /** @var list<GH10889Hand> $hands */
+        $hands = $this->_em
+            ->getRepository(GH10889Hand::class)
+            ->createQueryBuilder('hand')
+            ->leftJoin('hand.thumb', 'thumb')->addSelect('thumb')
+            ->getQuery()
+            ->getResult();
+
+        $this->assertArrayHasKey(0, $hands);
+        $this->assertEquals(1, $hands[0]->user->id);
+        $this->assertNull($hands[0]->thumb);
+    }
+}
+
+/**
+ * @ORM\Entity
+ */
+class GH10889User
+{
+    /**
+     * @ORM\Id
+     * @ORM\Column(type="integer")
+     * @ORM\GeneratedValue
+     *
+     * @var int
+     */
+    public $id;
+}
+
+/**
+ * @ORM\Entity
+ */
+class GH10889Finger
+{
+    /**
+     * @ORM\Id
+     * @ORM\Column(type="integer")
+     * @ORM\GeneratedValue
+     *
+     * @var int
+     */
+    public $id;
+}
+
+/**
+ * @ORM\Entity
+ */
+class GH10889Hand
+{
+    /**
+     * @ORM\Id
+     * @ORM\OneToOne(targetEntity="GH10889User")
+     * @ORM\GeneratedValue
+     *
+     * @var GH10889User
+     */
+    public $user;
+
+    /**
+     * @ORM\ManyToOne(targetEntity="GH10889Finger")
+     *
+     * @var GH10889Finger|null
+     */
+    public $thumb;
+
+    public function __construct(GH10889User $user, ?GH10889Finger $thumb)
+    {
+        $this->user  = $user;
+        $this->thumb = $thumb;
+    }
+}