Update serializer.rst

shows the new way to define a `circular_reference_handler` on the nromalizer

Author: Raulnet

components/serializer.rst

@@ -922,17 +922,22 @@ The ``setCircularReferenceLimit()`` method of this normalizer sets the number
 of times it will serialize the same object before considering it a circular
 reference. Its default value is ``1``.
 
+.. deprecated:: 4.2
+
+    The :method:`Symfony\\Component\\Serializer\\Normalizer\\AbstractNormalizer::setCircularReferenceHandler`
+    method is deprecated since Symfony 4.2, use the "circular_reference_handler" key of the context instead.
+
 Instead of throwing an exception, circular references can also be handled
 by custom callables. This is especially useful when serializing entities
 having unique identifiers::
 
     $encoder = new JsonEncoder();
-    $normalizer = new ObjectNormalizer();
-
-    // all callback parameters are optional (you can omit the ones you don't use)
-    $normalizer->setCircularReferenceHandler(function ($object, string $format = null, array $context = []) {
-        return $object->getName();
-    });
+    $defaultContext = [
+            AbstractNormalizer::CIRCULAR_REFERENCE_HANDLER => function ($object, $format, $context) {
+                return $object->getName();
+            }
+        ];
+    $normalizer = new ObjectNormalizer(null, null, null, null, null, null, $defaultContext);
 
     $serializer = new Serializer([$normalizer], [$encoder]);
     var_dump($serializer->serialize($org, 'json'));