Resolving $this usage outside a class on form.rst

This commit take care of the framework use code examples only.

The "Creating a simple Form" define the coding place to be into a controller action method. Unlikely, the documentation consider into the other examples that the reader will know the place of the sample code. This does not allow the examples to be standalone and can lead some disappointment for which one want to have informations about a single section.

This commit offer to place the code samples into the default controller to create a logic use of the "$this" special variable.

Author: matthieu88160

components/form.rst

@@ -444,14 +444,29 @@ builder:
 
     .. code-block:: php-symfony
 
-        $defaults = array(
-            'dueDate' => new \DateTime('tomorrow'),
-        );
+        // src/Acme/TaskBundle/Controller/DefaultController.php
+        namespace Acme\TaskBundle\Controller;
 
-        $form = $this->createFormBuilder($defaults)
-            ->add('task', 'text')
-            ->add('dueDate', 'date')
-            ->getForm();
+        use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+        use Symfony\Component\Form\Extension\Core\Type\TextType;
+        use Symfony\Component\Form\Extension\Core\Type\DateType;
+
+        class DefaultController extends Controller
+        {
+            public function newAction(Request $request)
+            {
+                $defaults = array(
+                    'dueDate' => new \DateTime('tomorrow'),
+                );
+
+                $form = $this->createFormBuilder($defaults)
+                    ->add('task', 'text')
+                    ->add('dueDate', 'date')
+                    ->getForm();
+
+                // ...
+            }
+        }
 
 .. tip::
 
@@ -511,16 +526,23 @@ by ``handleRequest()`` to determine whether a form has been submitted):
 
     .. code-block:: php-symfony
 
-        // ...
+        // src/Acme/TaskBundle/Controller/DefaultController.php
+        namespace Acme\TaskBundle\Controller;
+
+        use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+        use Symfony\Component\Form\Extension\Core\Type\FormType;
 
-        public function searchAction()
+        class DefaultController extends Controller
         {
-            $formBuilder = $this->createFormBuilder(null, array(
-                'action' => '/search',
-                'method' => 'GET',
-            ));
+            public function searchAction()
+            {
+                $formBuilder = $this->createFormBuilder(null, array(
+                    'action' => '/search',
+                    'method' => 'GET',
+                ));
 
-            // ...
+                // ...
+            }
         }
 
 .. _component-form-intro-handling-submission:
@@ -562,26 +584,34 @@ method:
 
     .. code-block:: php-symfony
 
-        // ...
+        // src/Acme/TaskBundle/Controller/DefaultController.php
+        namespace Acme\TaskBundle\Controller;
 
-        public function newAction(Request $request)
+        use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+        use Symfony\Component\Form\Extension\Core\Type\TextType;
+        use Symfony\Component\Form\Extension\Core\Type\DateType;
+
+        class DefaultController extends Controller
         {
-            $form = $this->createFormBuilder()
-                ->add('task', 'text')
-                ->add('dueDate', 'date')
-                ->getForm();
+            public function newAction(Request $request)
+            {
+                $form = $this->createFormBuilder()
+                    ->add('task', 'text')
+                    ->add('dueDate', 'date')
+                    ->getForm();
 
-            $form->handleRequest($request);
+                $form->handleRequest($request);
 
-            if ($form->isSubmitted() && $form->isValid()) {
-                $data = $form->getData();
+                if ($form->isSubmitted() && $form->isValid()) {
+                    $data = $form->getData();
 
-                // ... perform some action, such as saving the data to the database
+                    // ... perform some action, such as saving the data to the database
 
-                return $this->redirectToRoute('task_success');
-            }
+                    return $this->redirectToRoute('task_success');
+                }
 
-            // ...
+                // ...
+            }
         }
 
 This defines a common form "workflow", which contains 3 different possibilities:
@@ -628,20 +658,31 @@ option when building each field:
 
     .. code-block:: php-symfony
 
+        // src/Acme/TaskBundle/Controller/DefaultController.php
+        namespace Acme\TaskBundle\Controller;
+
+        use Symfony\Bundle\FrameworkBundle\Controller\Controller;
         use Symfony\Component\Validator\Constraints\NotBlank;
         use Symfony\Component\Validator\Constraints\Type;
 
-        $form = $this->createFormBuilder()
-            ->add('task', 'text', array(
-                'constraints' => new NotBlank(),
-            ))
-            ->add('dueDate', 'date', array(
-                'constraints' => array(
-                    new NotBlank(),
-                    new Type(\DateTime::class),
-                )
-            ))
-            ->getForm();
+        class DefaultController extends Controller
+        {
+            public function newAction(Request $request)
+            {
+                $form = $this->createFormBuilder()
+                    ->add('task', 'text', array(
+                        'constraints' => new NotBlank(),
+                    ))
+                    ->add('dueDate', 'date', array(
+                        'constraints' => array(
+                            new NotBlank(),
+                            new Type(\DateTime::class),
+                        )
+                    ))
+                    ->getForm();
+                // ...
+            }
+        }
 
 When the form is bound, these validation constraints will be applied automatically
 and the errors will display next to the fields on error.