Put actual value instead of index inside $originalEntityData. (#9244)

This fixes a bug with redundant UPDATE queries, that are executed when some entity uses foreign index of other entity as a primary key. This happens when after inserting related entities with $em->flush() call, you do the second $em->flush() without changing any data inside entities.
Fixes GH8217.

Co-authored-by: ivan <ivan.strygin@managinglife.com>

lib/Doctrine/ORM/UnitOfWork.php

@@ -1166,14 +1166,16 @@ private function addToEntityIdentifiersAndEntityMap(
         $identifier = [];
 
         foreach ($class->getIdentifierFieldNames() as $idField) {
-            $value = $class->getFieldValue($entity, $idField);
+            $origValue = $class->getFieldValue($entity, $idField);
 
+            $value = null;
             if (isset($class->associationMappings[$idField])) {
                 // NOTE: Single Columns as associated identifiers only allowed - this constraint it is enforced.
-                $value = $this->getSingleIdentifierValue($value);
+                $value = $this->getSingleIdentifierValue($origValue);
             }
 
-            $identifier[$idField] = $this->originalEntityData[$oid][$idField] = $value;
+            $identifier[$idField]                     = $value ?? $origValue;
+            $this->originalEntityData[$oid][$idField] = $origValue;
         }
 
         $this->entityStates[$oid]      = self::STATE_MANAGED;

tests/Doctrine/Tests/ORM/Functional/Ticket/GH8217Test.php

@@ -0,0 +1,108 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
+use Doctrine\ORM\Mapping\Column;
+use Doctrine\ORM\Mapping\Entity;
+use Doctrine\ORM\Mapping\GeneratedValue;
+use Doctrine\ORM\Mapping\Id;
+use Doctrine\ORM\Mapping\JoinColumn;
+use Doctrine\ORM\Mapping\ManyToOne;
+use Doctrine\ORM\Mapping\OneToMany;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+use function count;
+
+final class GH8217Test extends OrmFunctionalTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->setUpEntitySchema(
+            [
+                GH8217Collection::class,
+                GH8217CollectionItem::class,
+            ]
+        );
+    }
+
+    /**
+     * @group GH-8217
+     */
+    public function testNoQueriesAfterSecondFlush(): void
+    {
+        $collection = new GH8217Collection();
+        $collection->addItem(new GH8217CollectionItem($collection, 0));
+        $collection->addItem(new GH8217CollectionItem($collection, 1));
+        $this->_em->persist($collection);
+        $this->_em->flush();
+
+        $logger                         = $this->_sqlLoggerStack;
+        $queriesNumberBeforeSecondFlush = count($logger->queries);
+        $this->_em->flush();
+        $queriesNumberAfterSecondFlush = count($logger->queries);
+        self::assertEquals($queriesNumberBeforeSecondFlush, $queriesNumberAfterSecondFlush);
+    }
+}
+
+/**
+ * @Entity
+ */
+class GH8217Collection
+{
+    /**
+     * @var int
+     * @Id
+     * @Column(type="integer")
+     * @GeneratedValue
+     */
+    public $id;
+
+    /**
+     * @psalm-var Collection<int, GH8217CollectionItem>
+     * @OneToMany(targetEntity="GH8217CollectionItem", mappedBy="collection",
+     *     cascade={"persist", "remove"}, orphanRemoval=true)
+     */
+    public $items;
+
+    public function __construct()
+    {
+        $this->items = new ArrayCollection();
+    }
+
+    public function addItem(GH8217CollectionItem $item): void
+    {
+        $this->items->add($item);
+    }
+}
+
+/**
+ * @Entity
+ */
+class GH8217CollectionItem
+{
+    /**
+     * @var GH8217Collection
+     * @Id
+     * @ManyToOne(targetEntity="GH8217Collection", inversedBy="items")
+     * @JoinColumn(name="id", referencedColumnName="id")
+     */
+    public $collection;
+
+    /**
+     * @var int
+     * @Id
+     * @Column(type="integer", options={"unsigned": true})
+     */
+    public $collectionIndex;
+
+    public function __construct(GH8217Collection $collection, int $collectionIndex)
+    {
+        $this->collection      = $collection;
+        $this->collectionIndex = $collectionIndex;
+    }
+}