[WIP] Allow deserializing null

src/DeserializationContext.php

@@ -13,6 +13,11 @@ class DeserializationContext extends Context
      */
     private $depth = 0;
 
+    /**
+     * @var bool
+     */
+    private $deserializeNull = true;
+
     public static function create(): self
     {
         return new self();
@@ -33,6 +38,25 @@ public function increaseDepth(): void
         $this->depth += 1;
     }
 
+    /**
+     * Set if NULLs should be deserialized (TRUE) ot not (FALSE)
+     */
+    public function setDeserializeNull(bool $bool): self
+    {
+        $this->deserializeNull = $bool;
+
+        return $this;
+    }
+
+    /**
+     * Returns TRUE when NULLs should be deserialized
+     * Returns FALSE when NULLs should not be deserialized
+     */
+    public function shouldDeserializeNull(): bool
+    {
+        return $this->deserializeNull;
+    }
+
     public function decreaseDepth(): void
     {
         if ($this->depth <= 0) {

src/GraphNavigator/DeserializationGraphNavigator.php

@@ -6,6 +6,7 @@
 
 use JMS\Serializer\Accessor\AccessorStrategyInterface;
 use JMS\Serializer\Construction\ObjectConstructorInterface;
+use JMS\Serializer\Context;
 use JMS\Serializer\DeserializationContext;
 use JMS\Serializer\EventDispatcher\EventDispatcher;
 use JMS\Serializer\EventDispatcher\EventDispatcherInterface;
@@ -23,6 +24,7 @@
 use JMS\Serializer\Metadata\ClassMetadata;
 use JMS\Serializer\NullAwareVisitorInterface;
 use JMS\Serializer\Visitor\DeserializationVisitorInterface;
+use JMS\Serializer\VisitorInterface;
 use Metadata\MetadataFactoryInterface;
 
 /**
@@ -74,6 +76,11 @@ final class DeserializationGraphNavigator extends GraphNavigator implements Grap
      */
     private $accessor;
 
+    /**
+     * @var bool
+     */
+    private $shouldDeserializeNull;
+
     public function __construct(
         MetadataFactoryInterface $metadataFactory,
         HandlerRegistryInterface $handlerRegistry,
@@ -92,6 +99,12 @@ public function __construct(
         }
     }
 
+    public function initialize(VisitorInterface $visitor, Context $context): void
+    {
+        parent::initialize($visitor, $context);
+        $this->shouldDeserializeNull = $context->shouldDeserializeNull();
+    }
+
     /**
      * Called for each node of the graph that is being traversed.
      *
@@ -109,10 +122,13 @@ public function accept($data, ?array $type = null)
         }
         // Sometimes data can convey null but is not of a null type.
         // Visitors can have the power to add this custom null evaluation
-        if ($this->visitor instanceof NullAwareVisitorInterface && true === $this->visitor->isNull($data)) {
+        // If null is explicitly allowed we should skip this
+        if ($this->visitor instanceof NullAwareVisitorInterface
+            && true === $this->visitor->isNull($data)
+            && true === $this->shouldDeserializeNull
+        ) {
             $type = ['name' => 'NULL', 'params' => []];
         }
-
         switch ($type['name']) {
             case 'NULL':
                 return $this->visitor->visitNull($data, $type);
@@ -153,9 +169,11 @@ public function accept($data, ?array $type = null)
                 // before loading metadata because the type name might not be a class, but
                 // could also simply be an artifical type.
                 if (null !== $handler = $this->handlerRegistry->getHandler(GraphNavigatorInterface::DIRECTION_DESERIALIZATION, $type['name'], $this->format)) {
-                    $rs = \call_user_func($handler, $this->visitor, $data, $type, $this->context);
-                    $this->context->decreaseDepth();
-
+                    try {
+                        $rs = \call_user_func($handler, $this->visitor, $data, $type, $this->context);
+                    } finally {
+                        $this->context->decreaseDepth();
+                    }
                     return $rs;
                 }
 
@@ -201,6 +219,7 @@ public function accept($data, ?array $type = null)
                     $this->context->pushPropertyMetadata($propertyMetadata);
                     try {
                         $v = $this->visitor->visitProperty($propertyMetadata, $data);
+
                         $this->accessor->setValue($object, $v, $propertyMetadata, $this->context);
                     } catch (NotAcceptableException $e) {
                     }

src/JsonDeserializationVisitor.php

@@ -11,7 +11,7 @@
 use JMS\Serializer\Metadata\PropertyMetadata;
 use JMS\Serializer\Visitor\DeserializationVisitorInterface;
 
-final class JsonDeserializationVisitor extends AbstractVisitor implements DeserializationVisitorInterface
+final class JsonDeserializationVisitor extends AbstractVisitor implements NullAwareVisitorInterface, DeserializationVisitorInterface
 {
     /**
      * @var int
@@ -169,7 +169,7 @@ public function visitProperty(PropertyMetadata $metadata, $data)
             throw new NotAcceptableException();
         }
 
-        return null !== $data[$name] ? $this->navigator->accept($data[$name], $metadata->type) : null;
+        return $this->navigator->accept($data[$name], $metadata->type);
     }
 
     /**
@@ -237,4 +237,12 @@ public function prepare($str)
                 throw new RuntimeException('Could not decode JSON.');
         }
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function isNull($value): bool
+    {
+        return null === $value;
+    }
 }

tests/Fixtures/InitializedBlogPostConstructor.php

@@ -14,9 +14,15 @@ class InitializedBlogPostConstructor implements ObjectConstructorInterface
 {
     private $fallback;
 
-    public function __construct()
+    /**
+     * @var BlogPost
+     */
+    private $blogPost;
+
+    public function __construct(BlogPost $blogPost)
     {
         $this->fallback = new UnserializeObjectConstructor();
+        $this->blogPost = $blogPost;
     }
 
     public function construct(DeserializationVisitorInterface $visitor, ClassMetadata $metadata, $data, array $type, DeserializationContext $context): ?object
@@ -25,6 +31,6 @@ public function construct(DeserializationVisitorInterface $visitor, ClassMetadat
             return $this->fallback->construct($visitor, $metadata, $data, $type, $context);
         }
 
-        return new BlogPost('This is a nice title.', new Author('Foo Bar'), new \DateTime('2011-07-30 00:00', new \DateTimeZone('UTC')), new Publisher('Bar Foo'));
+        return $this->blogPost;
     }
 }

tests/Fixtures/ObjectWithNullObject.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace JMS\Serializer\Tests\Fixtures;
+
+use JMS\Serializer\Annotation\Type;
+
+class ObjectWithNullObject
+{
+    /**
+     * @var null
+     * @Type("NullObject")
+     */
+    private $nullProperty;
+
+    /**
+     * @return null
+     */
+    public function getNullProperty()
+    {
+        return $this->nullProperty;
+    }
+}

tests/Serializer/BaseSerializationTest.php

@@ -76,6 +76,7 @@
 use JMS\Serializer\Tests\Fixtures\ObjectWithIntListAndIntMap;
 use JMS\Serializer\Tests\Fixtures\ObjectWithIterator;
 use JMS\Serializer\Tests\Fixtures\ObjectWithLifecycleCallbacks;
+use JMS\Serializer\Tests\Fixtures\ObjectWithNullObject;
 use JMS\Serializer\Tests\Fixtures\ObjectWithNullProperty;
 use JMS\Serializer\Tests\Fixtures\ObjectWithToString;
 use JMS\Serializer\Tests\Fixtures\ObjectWithTypedArraySetter;
@@ -209,6 +210,25 @@ public function testDeserializeNullObject()
         self::assertNull($dObj->getNullProperty());
     }
 
+    public function testDeserializeNullObjectWithHandler()
+    {
+        if (!$this->hasDeserializer()) {
+            $this->markTestSkipped(sprintf('No deserializer available for format `%s`', $this->getFormat()));
+        }
+        $ctx = DeserializationContext::create()
+            ->setDeserializeNull(false);
+
+        /** @var ObjectWithNullObject $dObj */
+        $dObj = $this->serializer->deserialize(
+            $this->getContent('simple_object_nullable'),
+            ObjectWithNullObject::class,
+            $this->getFormat(),
+            $ctx
+        );
+
+        self::assertSame('nullObject', $dObj->getNullProperty());
+    }
+
     /**
      * @expectedException \JMS\Serializer\Exception\NotAcceptableException
      * @dataProvider getTypes
@@ -730,14 +750,13 @@ public function testBlogPost()
 
     public function testDeserializingNull()
     {
-        $objectConstructor = new InitializedBlogPostConstructor();
+        $post = new BlogPost('This is a nice title.', $author = new Author('Foo Bar'), new \DateTime('2011-07-30 00:00', new \DateTimeZone('UTC')), new Publisher('Bar Foo'));
+        $objectConstructor = new InitializedBlogPostConstructor($post);
 
         $builder = SerializerBuilder::create();
         $builder->setObjectConstructor($objectConstructor);
         $this->serializer = $builder->build();
 
-        $post = new BlogPost('This is a nice title.', $author = new Author('Foo Bar'), new \DateTime('2011-07-30 00:00', new \DateTimeZone('UTC')), new Publisher('Bar Foo'));
-
         $this->setField($post, 'author', null);
         $this->setField($post, 'publisher', null);
 
@@ -751,7 +770,42 @@ public function testDeserializingNull()
             self::assertAttributeSame(false, 'published', $deserialized);
             self::assertAttributeSame(false, 'reviewed', $deserialized);
             self::assertAttributeEquals(new ArrayCollection(), 'comments', $deserialized);
-            self::assertEquals(null, $this->getField($deserialized, 'author'));
+            self::assertAttributeSame(null, 'author', $deserialized);
+            self::assertAttributeSame(null, 'tag', $deserialized);
+        }
+    }
+
+    public function testDeserializingNullAllowed()
+    {
+        $savedPost = new BlogPost('This is a nice title.', $author = new Author('Foo Bar'), new \DateTime('2011-07-30 00:00', new \DateTimeZone('UTC')), $publisher = new Publisher('Bar Foo'));
+        $savedPost->addTag(new Tag('foo'));
+        $initialTag = $this->getField($savedPost, 'tag');
+
+        $objectConstructor = new InitializedBlogPostConstructor($savedPost);
+
+        $builder = SerializerBuilder::create();
+        $builder->setObjectConstructor($objectConstructor);
+        $this->serializer = $builder->build();
+
+        $post = clone $savedPost;
+        $this->setField($post, 'author', null);
+        $this->setField($post, 'publisher', null);
+        $this->setField($post, 'tag', null);
+
+        if ($this->hasDeserializer()) {
+            $ctx =  DeserializationContext::create();
+            $ctx->setDeserializeNull(false);
+
+            $deserialized = $this->deserialize($this->serialize($post), get_class($post), $ctx);
+
+            self::assertEquals('2011-07-30T00:00:00+00:00', $this->getField($deserialized, 'createdAt')->format(\DateTime::ATOM));
+            self::assertAttributeEquals('This is a nice title.', 'title', $deserialized);
+            self::assertAttributeSame(false, 'published', $deserialized);
+            self::assertAttributeSame(false, 'reviewed', $deserialized);
+            self::assertAttributeEquals(new ArrayCollection(), 'comments', $deserialized);
+            self::assertAttributeEquals($author, 'author', $deserialized);
+            self::assertAttributeEquals($publisher, 'publisher', $deserialized);
+            self::assertAttributeEquals($initialTag, 'tag', $deserialized);
         }
     }
 
@@ -1668,7 +1722,14 @@ static function (DeserializationVisitorInterface $visitor, $data, $type, Context
                 return $list;
             }
         );
-
+        $this->handlerRegistry->registerHandler(
+            GraphNavigatorInterface::DIRECTION_DESERIALIZATION,
+            'NullObject',
+            $this->getFormat(),
+            static function (DeserializationVisitorInterface $visitor, $data, $type, Context $context) {
+                return 'nullObject';
+            }
+        );
         $this->dispatcher = new EventDispatcher();
         $this->dispatcher->addSubscriber(new DoctrineProxySubscriber());
 

tests/Serializer/GraphNavigatorTest.php

@@ -141,7 +141,6 @@ protected function setUp()
             ->enableOriginalConstructor()
             ->setMethodsExcept(['getExclusionStrategy'])
             ->getMock();
-
         $this->deserializationContext = $this->getMockBuilder(DeserializationContext::class)
             ->enableOriginalConstructor()
             ->setMethodsExcept(['getExclusionStrategy'])

tests/Serializer/XmlSerializationTest.php

@@ -368,6 +368,11 @@ public function testDeserializingNull()
         $this->markTestSkipped('Not supported in XML.');
     }
 
+    public function testDeserializingNullAllowed()
+    {
+        $this->markTestSkipped('Not supported in XML.');
+    }
+
     public function testObjectWithXmlNamespaces()
     {
         $object = new ObjectWithXmlNamespaces('This is a nice title.', 'Foo Bar', new \DateTime('2011-07-30 00:00', new \DateTimeZone('UTC')), 'en');