fix(serializer): prevent api_platform_output context from leaking to nested non-resource objects

src/Serializer/AbstractItemNormalizer.php

@@ -116,7 +116,7 @@ public function supportsNormalization(mixed $data, ?string $format = null, array
             return true;
         }
 
-        if (isset($context['api_platform_output']) && ($context['resource_class'] ?? null) === $class) {
+        if (isset($context['api_platform_output_class']) && $context['api_platform_output_class'] === $class) {
             return true;
         }
 
@@ -152,6 +152,7 @@ public function normalize(mixed $data, ?string $format = null, array $context =
             $context['resource_class'] = $outputClass;
             $context['api_sub_level'] = true;
             $context['api_platform_output'] = true;
+            $context['api_platform_output_class'] = $outputClass;
             $context[self::ALLOW_EXTRA_ATTRIBUTES] = false;
 
             return $this->serializer->normalize($data, $format, $context);
@@ -221,7 +222,7 @@ public function supportsDenormalization(mixed $data, string $type, ?string $form
             return true;
         }
 
-        if (isset($context['api_platform_input']) && ($context['resource_class'] ?? null) === $type) {
+        if (isset($context['api_platform_input_class']) && $context['api_platform_input_class'] === $type) {
             return true;
         }
 
@@ -243,6 +244,7 @@ public function denormalize(mixed $data, string $type, ?string $format = null, a
             unset($context['input'], $context['operation'], $context['operation_name'], $context['uri_variables']);
             $context['resource_class'] = $inputClass;
             $context['api_platform_input'] = true;
+            $context['api_platform_input_class'] = $inputClass;
 
             try {
                 return $this->serializer->denormalize($data, $inputClass, $format, $context);

src/Serializer/Tests/AbstractItemNormalizerTest.php

@@ -1909,12 +1909,10 @@ public function testSupportsDenormalizationWithApiPlatformInputContext(): void
 
         $this->assertFalse($normalizer->supportsDenormalization([], \stdClass::class));
         $this->assertTrue($normalizer->supportsDenormalization([], \stdClass::class, null, [
-            'api_platform_input' => true,
-            'resource_class' => \stdClass::class,
+            'api_platform_input_class' => \stdClass::class,
         ]));
         $this->assertFalse($normalizer->supportsDenormalization([], \stdClass::class, null, [
-            'api_platform_input' => true,
-            'resource_class' => 'SomeOtherClass',
+            'api_platform_input_class' => 'SomeOtherClass',
         ]));
     }
 
@@ -1933,12 +1931,10 @@ public function testSupportsNormalizationWithApiPlatformOutputContext(): void
         $std = new \stdClass();
         $this->assertFalse($normalizer->supportsNormalization($std));
         $this->assertTrue($normalizer->supportsNormalization($std, null, [
-            'api_platform_output' => true,
-            'resource_class' => \stdClass::class,
+            'api_platform_output_class' => \stdClass::class,
         ]));
         $this->assertFalse($normalizer->supportsNormalization($std, null, [
-            'api_platform_output' => true,
-            'resource_class' => 'SomeOtherClass',
+            'api_platform_output_class' => 'SomeOtherClass',
         ]));
     }
 }

tests/Fixtures/TestBundle/ApiResource/DummyDtoNameConverted.php

@@ -19,6 +19,7 @@
 use ApiPlatform\Metadata\Post;
 use ApiPlatform\Tests\Fixtures\TestBundle\Dto\InputDtoWithNameConverter;
 use ApiPlatform\Tests\Fixtures\TestBundle\Dto\OutputDtoWithNameConverter;
+use ApiPlatform\Tests\Fixtures\TestBundle\Enum\GenderTypeEnum;
 
 #[ApiResource(
     operations: [
@@ -40,12 +41,13 @@ class DummyDtoNameConverted
     public function __construct(
         public ?int $id = null,
         public ?string $nameConverted = null,
+        public ?GenderTypeEnum $gender = null,
     ) {
     }
 
     public static function provide(Operation $operation, array $uriVariables = [], array $context = []): self
     {
-        return new self(id: 1, nameConverted: 'converted');
+        return new self(id: 1, nameConverted: 'converted', gender: GenderTypeEnum::MALE);
     }
 
     /**

tests/Fixtures/TestBundle/Dto/OutputDtoWithNameConverter.php

@@ -13,7 +13,10 @@
 
 namespace ApiPlatform\Tests\Fixtures\TestBundle\Dto;
 
+use ApiPlatform\Tests\Fixtures\TestBundle\Enum\GenderTypeEnum;
+
 class OutputDtoWithNameConverter
 {
     public ?string $nameConverted = null;
+    public ?GenderTypeEnum $gender = null;
 }

tests/Functional/InputOutputNameConverterTest.php

@@ -63,4 +63,18 @@ public function testOutputDtoNameConverterIsApplied(): void
         $this->assertArrayHasKey('name_converted', $data);
         $this->assertSame('converted', $data['name_converted']);
     }
+
+    /**
+     * Reproduces issue #7785: enum properties in output DTOs were serialized as
+     * {"@type": "...", "@id": "..."} objects instead of their scalar value.
+     */
+    public function testOutputDtoEnumPropertySerializedAsScalar(): void
+    {
+        $response = self::createClient()->request('GET', '/dummy_dto_name_converted/1');
+
+        $this->assertResponseIsSuccessful();
+        $data = $response->toArray();
+        $this->assertArrayHasKey('gender', $data);
+        $this->assertSame('male', $data['gender'], 'Enum in output DTO must serialize as its scalar value, not as a resource object.');
+    }
 }