From 40c633d41242945072fe8d734e69880b5e2e9c76 Mon Sep 17 00:00:00 2001
From: Kevin Bond <kevinbond@gmail.com>
Date: Thu, 2 Nov 2023 13:46:15 -0400
Subject: [PATCH] feat: make `PersistentCollection::first()` "extra" lazy

---
 lib/Doctrine/ORM/PersistentCollection.php     | 14 +++++
 .../Functional/ExtraLazyCollectionTest.php    | 59 +++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/lib/Doctrine/ORM/PersistentCollection.php b/lib/Doctrine/ORM/PersistentCollection.php
index c39252d7a27..f81d25bf9f0 100644
--- a/lib/Doctrine/ORM/PersistentCollection.php
+++ b/lib/Doctrine/ORM/PersistentCollection.php
@@ -590,6 +590,20 @@ public function __sleep(): array
         return ['collection', 'initialized'];
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public function first()
+    {
+        if (! $this->initialized && ! $this->isDirty && $this->getMapping()['fetch'] === ClassMetadata::FETCH_EXTRA_LAZY) {
+            $persister = $this->getUnitOfWork()->getCollectionPersister($this->getMapping());
+
+            return array_values($persister->slice($this, 0, 1))[0] ?? false;
+        }
+
+        return parent::first();
+    }
+
     /**
      * Extracts a slice of $length elements starting at position $offset from the Collection.
      *
diff --git a/tests/Doctrine/Tests/ORM/Functional/ExtraLazyCollectionTest.php b/tests/Doctrine/Tests/ORM/Functional/ExtraLazyCollectionTest.php
index e422d2cde78..2baddb79d2c 100644
--- a/tests/Doctrine/Tests/ORM/Functional/ExtraLazyCollectionTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/ExtraLazyCollectionTest.php
@@ -191,6 +191,65 @@ public function testCountOneToManyJoinedInheritance(): void
         self::assertCount(2, $otherClass->childClasses);
     }
 
+    /**
+     * @group non-cacheable
+     */
+    public function testFirstWhenInitialized(): void
+    {
+        $user = $this->_em->find(CmsUser::class, $this->userId);
+        $this->getQueryLog()->reset()->enable();
+        $user->groups->toArray();
+
+        self::assertTrue($user->groups->isInitialized());
+        self::assertInstanceOf(CmsGroup::class, $user->groups->first());
+        $this->assertQueryCount(1, 'Should only execute one query to initialize collection, no extra query for first().');
+    }
+
+    public function testFirstOnEmptyCollectionWhenInitialized(): void
+    {
+        foreach ($this->_em->getRepository(CmsGroup::class)->findAll() as $group) {
+            $this->_em->remove($group);
+        }
+
+        $this->_em->flush();
+
+        $user = $this->_em->find(CmsUser::class, $this->userId);
+        $this->getQueryLog()->reset()->enable();
+        $user->groups->toArray();
+
+        self::assertTrue($user->groups->isInitialized());
+        self::assertFalse($user->groups->first());
+        $this->assertQueryCount(1, 'Should only execute one query to initialize collection, no extra query for first().');
+    }
+
+    public function testFirstWhenNotInitialized(): void
+    {
+        $user = $this->_em->find(CmsUser::class, $this->userId);
+        $this->getQueryLog()->reset()->enable();
+
+        self::assertFalse($user->groups->isInitialized());
+        self::assertInstanceOf(CmsGroup::class, $user->groups->first());
+        self::assertFalse($user->groups->isInitialized());
+        $this->assertQueryCount(1, 'Should only execute one query for first().');
+    }
+
+    public function testFirstOnEmptyCollectionWhenNotInitialized(): void
+    {
+        foreach ($this->_em->getRepository(CmsGroup::class)->findAll() as $group) {
+            $this->_em->remove($group);
+        }
+
+        $this->_em->flush();
+
+        $user = $this->_em->find(CmsUser::class, $this->userId);
+        $this->getQueryLog()->reset()->enable();
+
+        self::assertFalse($user->groups->isInitialized());
+        self::assertFalse($user->groups->first());
+        self::assertFalse($user->groups->isInitialized());
+        $this->assertQueryCount(1, 'Should only execute one query for first().');
+    }
+
     /** @group DDC-546 */
     public function testFullSlice(): void
     {