fix(state): do not map to input class in ObjectMapperProvider

src/State/Provider/ObjectMapperProvider.php

@@ -41,7 +41,7 @@ public function __construct(
     public function provide(Operation $operation, array $uriVariables = [], array $context = []): object|array|null
     {
         $data = $this->decorated->provide($operation, $uriVariables, $context);
-        $class = $operation->getInput()['class'] ?? $operation->getOutput()['class'] ?? $operation->getClass();
+        $class = $operation->getOutput()['class'] ?? $operation->getClass();
 
         if (!$this->objectMapper || !$operation->canMap()) {
             return $data;

tests/Fixtures/TestBundle/ApiResource/MappedPatchResource.php

@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\ApiResource;
+
+use ApiPlatform\Doctrine\Orm\State\Options;
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\Get;
+use ApiPlatform\Metadata\Patch;
+use ApiPlatform\Metadata\Post;
+use ApiPlatform\Tests\Fixtures\TestBundle\Dto\MappedPatchInput;
+use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedPatchEntity;
+use Symfony\Component\ObjectMapper\Attribute\Map;
+
+#[ApiResource(
+    stateOptions: new Options(entityClass: MappedPatchEntity::class),
+    operations: [
+        new Get(),
+        new Post(input: MappedPatchInput::class),
+        new Patch(input: MappedPatchInput::class),
+    ],
+    normalizationContext: ['hydra_prefix' => false],
+)]
+#[Map(source: MappedPatchEntity::class)]
+class MappedPatchResource
+{
+    #[Map(if: false)]
+    public ?int $id = null;
+
+    public string $name;
+
+    public string $description;
+}

tests/Fixtures/TestBundle/Dto/MappedPatchInput.php

@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\Dto;
+
+use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedPatchEntity;
+use Symfony\Component\ObjectMapper\Attribute\Map;
+
+/**
+ * Input DTO for PATCH — maps directly to entity.
+ * Uses uninitialized properties so ObjectMapper skips unsent fields.
+ */
+#[Map(target: MappedPatchEntity::class)]
+class MappedPatchInput
+{
+    public string $name;
+
+    public string $description;
+}

tests/Fixtures/TestBundle/Entity/MappedPatchEntity.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+
+#[ORM\Entity]
+class MappedPatchEntity
+{
+    #[ORM\Column(type: 'integer')]
+    #[ORM\Id]
+    #[ORM\GeneratedValue(strategy: 'AUTO')]
+    public ?int $id = null;
+
+    #[ORM\Column]
+    public string $name;
+
+    #[ORM\Column]
+    public string $description;
+}

tests/Functional/MappingTest.php

@@ -17,6 +17,7 @@
 use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\BookStoreResource;
 use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\FirstResource;
 use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\Issue7563\BookDto;
+use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\MappedPatchResource;
 use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\MappedResource;
 use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\MappedResourceNoMap;
 use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\MappedResourceOdm;
@@ -31,6 +32,7 @@
 use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedEntity;
 use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedEntityNoMap;
 use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedEntitySourceOnly;
+use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedPatchEntity;
 use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedResourceWithRelationEntity;
 use ApiPlatform\Tests\Fixtures\TestBundle\Entity\MappedResourceWithRelationRelatedEntity;
 use ApiPlatform\Tests\Fixtures\TestBundle\Entity\SameEntity;
@@ -61,6 +63,7 @@ public static function getResources(): array
             MappedResourceNoMap::class,
             BookDto::class,
             BookStoreResource::class,
+            MappedPatchResource::class,
         ];
     }
 
@@ -477,4 +480,42 @@ public function testOutputDtoForCollectionRead(): void
             'author' => 'John Doe',
         ]);
     }
+
+    /**
+     * Test PATCH with input DTO + ObjectMapper: only client-sent fields should be updated.
+     * The input DTO uses uninitialized properties so ObjectMapper skips unsent fields.
+     */
+    public function testPatchWithInputDtoOnlyUpdatessentFields(): void
+    {
+        if (!$this->getContainer()->has('api_platform.object_mapper')) {
+            $this->markTestSkipped('ObjectMapper not installed');
+        }
+
+        if ($this->isMongoDB()) {
+            $this->markTestSkipped('MongoDB not tested');
+        }
+
+        $this->recreateSchema([MappedPatchEntity::class]);
+
+        $manager = $this->getManager();
+        $entity = new MappedPatchEntity();
+        $entity->name = 'original name';
+        $entity->description = 'original description';
+        $manager->persist($entity);
+        $manager->flush();
+
+        $id = $entity->id;
+
+        // PATCH only the name — description should remain unchanged
+        self::createClient()->request('PATCH', '/mapped_patch_resources/'.$id, [
+            'headers' => ['content-type' => 'application/merge-patch+json'],
+            'json' => ['name' => 'updated name'],
+        ]);
+
+        self::assertResponseIsSuccessful();
+        self::assertJsonContains([
+            'name' => 'updated name',
+            'description' => 'original description',
+        ]);
+    }
 }

tests/State/Provider/ObjectMapperProviderTest.php

@@ -169,22 +169,22 @@ public function testProvideMapsPaginator(): void
         $this->assertSame($targetResource2, $items[1]);
     }
 
-    public function testProvideMapsToInputClassWhenInputIsSet(): void
+    public function testProvideIgnoresInputClassAndMapsToOutputClass(): void
     {
         $sourceEntity = new SourceEntity();
-        $inputResource = new InputResource();
+        $outputResource = new OutputResource();
         $operation = new Patch(class: TargetResource::class, input: ['class' => InputResource::class], output: ['class' => OutputResource::class], map: true);
         $objectMapper = $this->createMock(ObjectMapperInterface::class);
         $objectMapper->expects($this->once())
             ->method('map')
-            ->with($sourceEntity, InputResource::class)
-            ->willReturn($inputResource);
+            ->with($sourceEntity, OutputResource::class)
+            ->willReturn($outputResource);
         $decorated = $this->createStub(ProviderInterface::class);
         $decorated->method('provide')->willReturn($sourceEntity);
         $provider = new ObjectMapperProvider($objectMapper, $decorated);
 
         $result = $provider->provide($operation);
-        $this->assertSame($inputResource, $result);
+        $this->assertSame($outputResource, $result);
     }
 
     public function testProvideMapsToOutputClassWhenNoInput(): void
@@ -205,6 +205,24 @@ public function testProvideMapsToOutputClassWhenNoInput(): void
         $this->assertSame($outputResource, $result);
     }
 
+    public function testProvideMapsToResourceClassWhenInputSetButNoOutput(): void
+    {
+        $sourceEntity = new SourceEntity();
+        $targetResource = new TargetResource();
+        $operation = new Patch(class: TargetResource::class, input: ['class' => InputResource::class], map: true);
+        $objectMapper = $this->createMock(ObjectMapperInterface::class);
+        $objectMapper->expects($this->once())
+            ->method('map')
+            ->with($sourceEntity, TargetResource::class)
+            ->willReturn($targetResource);
+        $decorated = $this->createStub(ProviderInterface::class);
+        $decorated->method('provide')->willReturn($sourceEntity);
+        $provider = new ObjectMapperProvider($objectMapper, $decorated);
+
+        $result = $provider->provide($operation);
+        $this->assertSame($targetResource, $result);
+    }
+
     public function testProvideMapsEmptyArray(): void
     {
         $operation = new Get(class: TargetResource::class, map: true);