Issue #2685097 by damiankloip, Wim Leers: Fatal error: Call to a member function normalize() on a non-object in XmlEncoder when encoding into xml and there are embedded objects in the response

core/modules/serialization/src/Encoder/XmlEncoder.php

@@ -4,6 +4,7 @@ namespace Drupal\serialization\Encoder;
 
 use Symfony\Component\Serializer\Encoder\EncoderInterface;
 use Symfony\Component\Serializer\Encoder\DecoderInterface;
+use Symfony\Component\Serializer\Encoder\SerializerAwareEncoder;
 use Symfony\Component\Serializer\Encoder\XmlEncoder as BaseXmlEncoder;
 
 /**
@@ -12,7 +13,7 @@ use Symfony\Component\Serializer\Encoder\XmlEncoder as BaseXmlEncoder;
  * This acts as a wrapper class for Symfony's XmlEncoder so that it is not
  * implementing NormalizationAwareInterface, and can be normalized externally.
  */
-class XmlEncoder implements EncoderInterface, DecoderInterface {
+class XmlEncoder extends SerializerAwareEncoder implements EncoderInterface, DecoderInterface {
 
   /**
    * The formats that this Encoder supports.
@@ -37,6 +38,7 @@ class XmlEncoder implements EncoderInterface, DecoderInterface {
   public function getBaseEncoder() {
     if (!isset($this->baseEncoder)) {
       $this->baseEncoder = new BaseXmlEncoder();
+      $this->baseEncoder->setSerializer($this->serializer);
     }
 
     return $this->baseEncoder;

core/modules/serialization/tests/src/Unit/Encoder/XmlEncoderTest.php

@@ -3,6 +3,9 @@
 namespace Drupal\Tests\serialization\Unit\Encoder;
 
 use Drupal\serialization\Encoder\XmlEncoder;
+use Symfony\Component\Serializer\Encoder\XmlEncoder as BaseXmlEncoder;
+use Symfony\Component\Serializer\Normalizer\GetSetMethodNormalizer;
+use Symfony\Component\Serializer\Serializer;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -31,7 +34,7 @@ class XmlEncoderTest extends UnitTestCase {
   protected $testArray = ['test' => 'test'];
 
   protected function setUp() {
-    $this->baseEncoder = $this->getMock('Symfony\Component\Serializer\Encoder\XmlEncoder');
+    $this->baseEncoder = $this->getMock(BaseXmlEncoder::class);
     $this->encoder = new XmlEncoder();
     $this->encoder->setBaseEncoder($this->baseEncoder);
   }
@@ -76,4 +79,26 @@ class XmlEncoderTest extends UnitTestCase {
     $this->assertEquals($this->testArray, $this->encoder->decode('test', 'test'));
   }
 
+  /**
+   * @covers ::getBaseEncoder
+   */
+  public function testDefaultEncoderHasSerializer() {
+    // The serializer should be set on the Drupal encoder, which should then
+    // set it on our default encoder.
+    $encoder = new XmlEncoder();
+    $serialzer = new Serializer([new GetSetMethodNormalizer()]);
+    $encoder->setSerializer($serialzer);
+    $base_encoder = $encoder->getBaseEncoder();
+    $this->assertInstanceOf(BaseXmlEncoder::class, $base_encoder);
+    // Test the encoder.
+    $base_encoder->encode(['a' => new TestObject()], 'xml');
+  }
+
+}
+
+class TestObject {
+  public function getA() {
+    return 'A';
+  }
+
 }