bug #36601 [Serializer] do not transform empty \Traversable to Array (soyuka)

nicolas-grekas · nicolas-grekas · commit 4528c1194b3a · 2020-05-01T23:09:03.000+02:00
This PR was merged into the 4.4 branch. Discussion ---------- [Serializer] do not transform empty \Traversable to Array | Q | A | ------------- | --- | Branch? | 4.4 | Bug fix? | yes | New feature? | no  | Deprecations? | no  | Tickets | na | License | MIT | Doc PR | na Today, using `PRESERVE_EMPTY_OBJECTS` ([introduced in 4.0](f28e826)), the JSON serialization of: ```php <?php $object = []; $object['foo'] = new \ArrayObject(); $object['bar'] = new \ArrayObject(['notempty']); $object['baz'] = new \ArrayObject(['nested' => new \ArrayObject()]); ``` Outputs: ```json {"foo":[],"bar":["notempty"],"baz":{"nested":[]}} ``` Instead of the expected: ```json {"foo":{},"bar":["notempty"],"baz":{"nested":{}}} ``` This issue comes from the Serializer that transforms `Traversable` to an Array [here](https://github.com/symfony/symfony/blob/11a707200d65d1142b681100fdfd5a9782f93f02/src/Symfony/Component/Serializer/Serializer.php#L159). Also, the `AbstractObjectNormalizer` [doesn't support Traversable](https://github.com/symfony/symfony/blob/11a707200d65d1142b681100fdfd5a9782f93f02/src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php#L134), but he allows to preserve empty objects. I propose this patch where the fix doesn't transform a `Traversable` to an Array. I see another way to patch this in which we could allow empty Traversable in the `AbstractObjectNormalizer` (not sure it's better though). See attached [other-fix.patch](https://github.com/symfony/symfony/files/4539865/other-fix.log) to see the alternative patch. Commits ------- e5c2029 Fix serializer do not transform empty \Traversable to Array
diff --git a/src/Symfony/Component/Serializer/Serializer.php b/src/Symfony/Component/Serializer/Serializer.php
@@ -157,6 +157,10 @@ public function normalize($data, $format = null, array $context = [])
         }
 
         if (\is_array($data) || $data instanceof \Traversable) {
+            if ($data instanceof \Countable && 0 === $data->count()) {
+                return $data;
+            }
+
             $normalized = [];
             foreach ($data as $key => $val) {
                 $normalized[$key] = $this->normalize($val, $format, $context);
diff --git a/src/Symfony/Component/Serializer/Tests/SerializerTest.php b/src/Symfony/Component/Serializer/Tests/SerializerTest.php
@@ -25,6 +25,7 @@
 use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
 use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactoryInterface;
 use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
+use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
 use Symfony\Component\Serializer\Normalizer\ArrayDenormalizer;
 use Symfony\Component\Serializer\Normalizer\CustomNormalizer;
 use Symfony\Component\Serializer\Normalizer\DenormalizerAwareInterface;
@@ -490,6 +491,26 @@ public function testNotNormalizableValueExceptionMessageForAResource()
         (new Serializer())->normalize(tmpfile());
     }
 
+    public function testNormalizePreserveEmptyArrayObject()
+    {
+        $serializer = new Serializer(
+          [
+              new PropertyNormalizer(),
+              new ObjectNormalizer(),
+              new ArrayDenormalizer(),
+          ],
+          [
+              'json' => new JsonEncoder(),
+          ]
+        );
+
+        $object = [];
+        $object['foo'] = new \ArrayObject();
+        $object['bar'] = new \ArrayObject(['notempty']);
+        $object['baz'] = new \ArrayObject(['nested' => new \ArrayObject()]);
+        $this->assertEquals('{"foo":{},"bar":["notempty"],"baz":{"nested":{}}}', $serializer->serialize($object, 'json', [AbstractObjectNormalizer::PRESERVE_EMPTY_OBJECTS => true]));
+    }
+
     private function serializerWithClassDiscriminator()
     {
         $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
