[Serializer] Add XmlEncoder context example

SirRFI · SirRFI · commit 66e31ea55f35 · 2021-06-14T19:25:11.000+02:00
diff --git a/components/serializer.rst b/components/serializer.rst
@@ -991,6 +991,40 @@ Option                          Description
     The ``decoder_ignored_node_types`` and ``encoder_ignored_node_types``
     options were introduced in Symfony 4.2.
 
+Example with custom ``context``::
+
+    use Symfony\Component\Serializer\Encoder\XmlEncoder;
+
+    // create encoder with specified options as new default settings
+    $xmlEncoder = new XmlEncoder(['xml_format_output' => true]);
+
+    $data = [
+        'id' => 'IDHNQIItNyQ',
+        'date' => '2019-10-24',
+    ];
+
+    // encode with default context
+    $xmlEncoder->encode($data, 'xml');
+    // outputs:
+    // <?xml version="1.0"?>
+    // <response>
+    //   <id>IDHNQIItNyQ</id>
+    //   <date>2019-10-24</date>
+    // </response>
+
+    // encode with modified context
+    $xmlEncoder->encode($data, 'xml', [
+        'xml_root_node_name' => 'track',
+        'encoder_ignored_node_types' => [
+            \XML_PI_NODE, // removes XML declaration (the leading xml tag)
+        ],
+    ]);
+    // outputs:
+    // <track>
+    //   <id>IDHNQIItNyQ</id>
+    //   <date>2019-10-24</date>
+    // </track>
+
 The ``YamlEncoder``
 ~~~~~~~~~~~~~~~~~~~
 
