code: public function newAction(Request $request)
      {
          $entity = new CustomField();
          
          //add the custom field group if defined in URL
          $cfGroupId = $request->query->get('customFieldsGroup', null);
          
          if ($cfGroupId !== null) {
              $cfGroup = $this->getDoctrine()->getManager()
                    ->getRepository('ChillCustomFieldsBundle:CustomFieldsGroup')
                    ->find($cfGroupId);
              if (!$cfGroup) {
                  throw $this->createNotFoundException('CustomFieldsGroup with id '
                        . $cfGroupId.' is not found !');
              }
              $entity->setCustomFieldsGroup($cfGroup);
          }
          
          $form   = $this->createCreateForm($entity, $request->query->get('type'));
  
          return $this->render('ChillCustomFieldsBundle:CustomField:new.html.twig', array(
              'entity' => $entity,
              'form'   => $form->createView(),
          ));
      }
docs: Displays a form to create a new CustomField entity.