document default context for the serializer

Author: dbu

reference/configuration/framework.rst

@@ -2743,6 +2743,18 @@ paths
 This option allows to define an array of paths with files or directories where
 the component will look for additional serialization files.
 
+default_context
+...............
+
+**type**: ``array`` **default**: ``[]``
+
+A map with default context options that will be used with each ``serialize`` and ``deserialize``
+call. This can be used for example to set the json encoding behaviour by setting ``json_encode_options``
+to a `json_encode flags bitmask`_.
+
+You can inspect the :ref:`serializer context builders <serializer-using-context-builders>`
+to discover the available settings.
+
 php_errors
 ~~~~~~~~~~
 
@@ -3573,6 +3585,7 @@ use the configuration of the first exception that matches ``instanceof``:
 .. _`blue/green deployment`: https://martinfowler.com/bliki/BlueGreenDeployment.html
 .. _`gulp-rev`: https://www.npmjs.com/package/gulp-rev
 .. _`webpack-manifest-plugin`: https://www.npmjs.com/package/webpack-manifest-plugin
+.. _`json_encode flags bitmask`: https://www.php.net/json_encode
 .. _`error_reporting PHP option`: https://www.php.net/manual/en/errorfunc.configuration.php#ini.error-reporting
 .. _`CSRF security attacks`: https://en.wikipedia.org/wiki/Cross-site_request_forgery
 .. _`session.sid_length PHP option`: https://www.php.net/manual/session.configuration.php#ini.session.sid-length

serializer.rst

@@ -130,14 +130,15 @@ configuration:
             serializer:
                 default_context:
                     enable_max_depth: true
+                    yaml_indentation: 2
 
     .. code-block:: xml
 
         <!-- config/packages/framework.xml -->
         <framework:config>
             <!-- ... -->
             <framework:serializer>
-                <default-context enable-max-depth="true"/>
+                <default-context enable-max-depth="true" yaml-indentation="2"/>
             </framework:serializer>
         </framework:config>
 
@@ -146,11 +147,13 @@ configuration:
         // config/packages/framework.php
         use Symfony\Config\FrameworkConfig;
         use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
+        use Symfony\Component\Serializer\Encoder\YamlEncoder;
 
         return static function (FrameworkConfig $framework) {
             $framework->serializer()
                 ->defaultContext([
-                    AbstractObjectNormalizer::ENABLE_MAX_DEPTH => true
+                    AbstractObjectNormalizer::ENABLE_MAX_DEPTH => true,
+                    YamlEncoder::YAML_INDENTATION => 2,
                 ])
             ;
         };