Skip native lazy object initialization for unmapped properties

docs/en/cookbook/lookup-reference.rst

@@ -14,6 +14,12 @@ need the referenced documents, you can use the ``$lookup`` stage in MongoDB's
 aggregation pipeline. It's similar to a SQL join, without duplication of data in
 the result set when there is many references to load.
 
+.. note::
+
+    Lazy loading of references only occurs when accessing an uninitialized mapped property.
+    If you access a property that is not mapped in Doctrine, that will not trigger
+    loading of the referenced document.
+
 Example setup
 -------------
 

src/Proxy/Factory/NativeLazyObjectFactory.php

@@ -12,8 +12,10 @@
 use Doctrine\Persistence\NotifyPropertyChanged;
 use LogicException;
 use ReflectionClass;
+use ReflectionProperty;
 use WeakMap;
 
+use function array_key_exists;
 use function count;
 
 use const PHP_VERSION_ID;
@@ -27,6 +29,9 @@ class NativeLazyObjectFactory implements ProxyFactory
     private readonly UnitOfWork $unitOfWork;
     private readonly LifecycleEventManager $lifecycleEventManager;
 
+    /** @var array<class-string, ReflectionProperty[]> */
+    private array $skippedProperties = [];
+
     public function __construct(
         DocumentManager $documentManager,
     ) {
@@ -68,13 +73,40 @@ public function getProxy(ClassMetadata $metadata, $identifier): object
 
         $metadata->propertyAccessors[$metadata->identifier]->setValue($proxy, $identifier);
 
+        foreach ($this->getSkippedProperties($metadata) as $property) {
+            $property->skipLazyInitialization($proxy);
+        }
+
         if (isset(self::$lazyObjects)) {
             self::$lazyObjects[$proxy] = true;
         }
 
         return $proxy;
     }
 
+    /** @return ReflectionProperty[] */
+    private function getSkippedProperties(ClassMetadata $metadata): array
+    {
+        if (isset($this->skippedProperties[$metadata->name])) {
+            return $this->skippedProperties[$metadata->name];
+        }
+
+        $skippedProperties = [];
+        foreach ($metadata->reflClass->getProperties() as $property) {
+            if (array_key_exists($property->name, $metadata->propertyAccessors)) {
+                continue;
+            }
+
+            if ($property->isVirtual()) {
+                continue;
+            }
+
+            $skippedProperties[] = $property;
+        }
+
+        return $this->skippedProperties[$metadata->name] = $skippedProperties;
+    }
+
     /** @internal Only for tests */
     public static function enableTracking(bool $enabled = true): void
     {

tests/Tests/Functional/ReferencesTest.php

@@ -15,6 +15,7 @@
 use Doctrine\ODM\MongoDB\Tests\BaseTestCase;
 use Documents\Account;
 use Documents\Address;
+use Documents\DocumentWithUnmappedProperties;
 use Documents\Group;
 use Documents\Phonenumber;
 use Documents\Profile;
@@ -28,6 +29,15 @@
 
 class ReferencesTest extends BaseTestCase
 {
+    public function testSkipInitializationForUnmappedProperties(): void
+    {
+        $loadedDocument = $this->dm->getReference(DocumentWithUnmappedProperties::class, '123');
+        $this->assertInstanceOf(DocumentWithUnmappedProperties::class, $loadedDocument);
+
+        // Accessing unmapped property should not initialize the document
+        self::assertSame('bar', $loadedDocument->foo);
+    }
+
     public function testManyDeleteReference(): void
     {
         $user = new User();