Supports nested "abstract" object while serializing and de-serializing

src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php

@@ -294,7 +294,7 @@ abstract class AbstractObjectNormalizer extends AbstractNormalizer
      */
     private function validateAndDenormalize(string $currentClass, string $attribute, $data, ?string $format, array $context)
     {
-        if (null === $this->propertyTypeExtractor || null === $types = $this->propertyTypeExtractor->getTypes($currentClass, $attribute)) {
+        if (null === $types = $this->getTypes($currentClass, $attribute)) {
             return $data;
         }
 
@@ -357,6 +357,36 @@ abstract class AbstractObjectNormalizer extends AbstractNormalizer
         throw new NotNormalizableValueException(sprintf('The type of the "%s" attribute for class "%s" must be one of "%s" ("%s" given).', $attribute, $currentClass, implode('", "', array_keys($expectedTypes)), gettype($data)));
     }
 
+    /**
+     * @return Type[]|null
+     */
+    private function getTypes(string $currentClass, string $attribute)
+    {
+        if (null === $this->propertyTypeExtractor) {
+            return null;
+        }
+
+        if (null !== $types = $this->propertyTypeExtractor->getTypes($currentClass, $attribute)) {
+            return $types;
+        }
+
+        if (null !== $this->classDiscriminatorResolver && null !== $discriminatorMapping = $this->classDiscriminatorResolver->getMappingForClass($currentClass)) {
+            if ($discriminatorMapping->getTypeProperty() === $attribute) {
+                return array(
+                    new Type(Type::BUILTIN_TYPE_STRING),
+                );
+            }
+
+            foreach ($discriminatorMapping->getTypesMapping() as $mappedClass) {
+                if (null !== $types = $this->propertyTypeExtractor->getTypes($mappedClass, $attribute)) {
+                    return $types;
+                }
+            }
+        }
+
+        return null;
+    }
+
     /**
      * Sets an attribute and apply the name converter if necessary.
      *

src/Symfony/Component/Serializer/Tests/Fixtures/DummyMessageNumberTwo.php

@@ -22,4 +22,19 @@ class DummyMessageNumberTwo implements DummyMessageInterface
      * @Groups({"two"})
      */
     public $three;
+
+    /**
+     * @var DummyMessageNumberOne
+     */
+    private $nested;
+
+    public function setNested(DummyMessageNumberOne $nested)
+    {
+        $this->nested = $nested;
+    }
+
+    public function getNested(): DummyMessageNumberOne
+    {
+        return $this->nested;
+    }
 }

src/Symfony/Component/Serializer/Tests/SerializerTest.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\Serializer\Tests;
 
 use Doctrine\Common\Annotations\AnnotationReader;
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\PropertyInfo\Extractor\ReflectionExtractor;
 use Symfony\Component\Serializer\Mapping\ClassDiscriminatorFromClassMetadata;
 use Symfony\Component\Serializer\Mapping\ClassDiscriminatorMapping;
 use Symfony\Component\Serializer\Mapping\ClassMetadata;
@@ -35,6 +36,7 @@ use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummyFirstChild;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractDummySecondChild;
 use Symfony\Component\Serializer\Tests\Fixtures\DummyMessageInterface;
 use Symfony\Component\Serializer\Tests\Fixtures\DummyMessageNumberOne;
+use Symfony\Component\Serializer\Tests\Fixtures\DummyMessageNumberTwo;
 use Symfony\Component\Serializer\Tests\Fixtures\TraversableDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\NormalizableTraversableDummy;
 use Symfony\Component\Serializer\Tests\Normalizer\TestNormalizer;
@@ -430,6 +432,22 @@ class SerializerTest extends TestCase
         $this->assertEquals('{"two":2,"type":"one"}', $serialized);
     }
 
+    public function testDeserializeAndSerializeNestedInterfacedObjectsWithTheClassMetadataDiscriminator()
+    {
+        $nested = new DummyMessageNumberOne();
+        $nested->one = 'foo';
+
+        $example = new DummyMessageNumberTwo();
+        $example->setNested($nested);
+
+        $serializer = $this->serializerWithClassDiscriminator();
+
+        $serialized = $serializer->serialize($example, 'json');
+        $deserialized = $serializer->deserialize($serialized, DummyMessageInterface::class, 'json');
+
+        $this->assertEquals($example, $deserialized);
+    }
+
     /**
      * @expectedException \Symfony\Component\Serializer\Exception\RuntimeException
      * @expectedExceptionMessage The type "second" has no mapped class for the abstract object "Symfony\Component\Serializer\Tests\Fixtures\DummyMessageInterface"
@@ -452,7 +470,7 @@ class SerializerTest extends TestCase
     {
         $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
 
-        return new Serializer(array(new ObjectNormalizer($classMetadataFactory, null, null, null, new ClassDiscriminatorFromClassMetadata($classMetadataFactory))), array('json' => new JsonEncoder()));
+        return new Serializer(array(new ObjectNormalizer($classMetadataFactory, null, null, new ReflectionExtractor(), new ClassDiscriminatorFromClassMetadata($classMetadataFactory))), array('json' => new JsonEncoder()));
     }
 }