Add new way of mapping form data

Author: yceruto

form/data_mappers.rst

@@ -189,6 +189,45 @@ method::
 Cool! When using the ``ColorType`` form, the custom data mapper methods will
 create a new ``Color`` object now.
 
+Mapping Form Fields Using Callbacks
+-----------------------------------
+
+Conveniently, you can also map data from and into a form field by using the
+``getter`` and ``setter`` options. For example, suppose you have a form with some
+fields and only one of them needs to be mapped in some special way or you only
+need to change how it's written into the underlying object. In that case, register
+a PHP callable that is able to write or read to/from that specific object::
+
+    public function buildForm(FormBuilderInterface $builder, array $options)
+    {
+        // ...
+
+        $builder->add('state', ChoiceType::class, [
+            'choices' => [
+                'active' => true,
+                'paused' => false,
+            ],
+            'getter' => function (Task $task, FormInterface $form): bool {
+                return !$task->isCancelled() && !$task->isPaused();
+            },
+            'setter' => function (Task &$task, bool $state, FormInterface $form): void {
+                if ($state) {
+                    $task->activate();
+                } else {
+                    $task->pause();
+                }
+            },
+        ]);
+    }
+
+If available, these options have priority over the property path accessor and
+the default data mapper will still use the :doc:`PropertyAccess component </components/property_access>`
+for the other form fields.
+
+.. versionadded:: 5.2
+
+    The ``getter`` and ``setter`` options were introduced in Symfony 5.2.
+
 .. caution::
 
     When a form has the ``inherit_data`` option set to ``true``, it does not use the data mapper and