feature symfony#19137 [Serializer] Allow to use easily static constructors (Ener-Getick)

This PR was merged into the 3.2-dev branch.

Discussion
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[Serializer] Allow to use easily static constructors

| Q             | A
| ------------- | ---
| Branch?       | "master"
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#19027 (comment)
| License       | MIT
| Doc PR        | -

This PR allows to simply use static constructors to instantiate objects with the serializer by extending the default normalizers.

Commits
-------

9be6484 [Serializer] Allow to use easily static constructors

Author: fabpot

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

@@ -251,6 +251,23 @@ protected function prepareForDenormalization($data)
         return (array) $data;
     }
 
+    /**
+     * Returns the method to use to construct an object. This method must be either
+     * the object constructor or static.
+     *
+     * @param array            $data
+     * @param string           $class
+     * @param array            $context
+     * @param \ReflectionClass $reflectionClass
+     * @param array|bool       $allowedAttributes
+     *
+     * @return \ReflectionMethod|null
+     */
+    protected function getConstructor(array &$data, $class, array &$context, \ReflectionClass $reflectionClass, $allowedAttributes)
+    {
+        return $reflectionClass->getConstructor();
+    }
+
     /**
      * Instantiates an object using constructor parameters when needed.
      *
@@ -282,7 +299,7 @@ protected function instantiateObject(array &$data, $class, array &$context, \Ref
             return $object;
         }
 
-        $constructor = $reflectionClass->getConstructor();
+        $constructor = $this->getConstructor($data, $class, $context, $reflectionClass, $allowedAttributes);
         if ($constructor) {
             $constructorParameters = $constructor->getParameters();
 
@@ -318,7 +335,11 @@ protected function instantiateObject(array &$data, $class, array &$context, \Ref
                 }
             }
 
-            return $reflectionClass->newInstanceArgs($params);
+            if ($constructor->isConstructor()) {
+                return $reflectionClass->newInstanceArgs($params);
+            } else {
+                return $constructor->invokeArgs(null, $params);
+            }
         }
 
         return new $class();

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

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Tests\Fixtures;
+
+class StaticConstructorDummy
+{
+    public $foo;
+    public $bar;
+    public $quz;
+
+    public static function create($foo)
+    {
+        $dummy = new self();
+        $dummy->quz = $foo;
+
+        return $dummy;
+    }
+
+    private function __construct()
+    {
+    }
+}

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

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Tests\Fixtures;
+
+use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
+
+/**
+ * @author Guilhem N. <egetick@gmail.com>
+ */
+class StaticConstructorNormalizer extends ObjectNormalizer
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function getConstructor(array &$data, $class, array &$context, \ReflectionClass $reflectionClass, $allowedAttributes)
+    {
+        if (is_a($class, StaticConstructorDummy::class, true)) {
+            return new \ReflectionMethod($class, 'create');
+        }
+
+        return parent::getConstructor($data, $class, $context, $reflectionClass, $allowedAttributes);
+    }
+}

src/Symfony/Component/Serializer/Tests/Normalizer/AbstractNormalizerTest.php

@@ -9,6 +9,8 @@
 use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
 use Symfony\Component\Serializer\Tests\Fixtures\AbstractNormalizerDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\ProxyDummy;
+use Symfony\Component\Serializer\Tests\Fixtures\StaticConstructorDummy;
+use Symfony\Component\Serializer\Tests\Fixtures\StaticConstructorNormalizer;
 
 /**
  * Provides a dummy Normalizer which extends the AbstractNormalizer.
@@ -103,4 +105,14 @@ public function testObjectToPopulateWithProxy()
 
         $this->assertSame('bar', $proxyDummy->getFoo());
     }
+
+    public function testObjectWithStaticConstructor()
+    {
+        $normalizer = new StaticConstructorNormalizer();
+        $dummy = $normalizer->denormalize(array('foo' => 'baz'), StaticConstructorDummy::class);
+
+        $this->assertInstanceOf(StaticConstructorDummy::class, $dummy);
+        $this->assertEquals('baz', $dummy->quz);
+        $this->assertNull($dummy->foo);
+    }
 }