class HtmlEntityFormController

class HtmlEntityFormController extends HtmlFormController {

  /**
   * {@inheritdoc}
   *
   * Due to reflection, the argument must be named $_entity_form. The parent
   * method has $request and $_form, but the parameter must match the route.
   */
  public function content(Request $request, $_entity_form) {
    return parent::content($request, $_entity_form);
  }

  /**
   * {@inheritdoc}
   *
   * Instead of a class name or service ID, $form_arg will be a string
   * representing the entity and operation being performed.
   * Consider the following route:
   * @code
   *   pattern: '/foo/{node}/bar'
   *   defaults:
   *     _entity_form: 'node.edit'
   * @endcode
   * This means that the edit form controller for the node entity will used.
   * If the entity type has a default form controller, only the name of the
   * entity {param} needs to be passed:
   * @code
   *   pattern: '/foo/{node}/baz'
   *   defaults:
   *     _entity_form: 'node'
   * @endcode
   */
  protected function getFormObject(Request $request, $form_arg) {
    $manager = $this->container
      ->get('plugin.manager.entity');

    // If no operation is provided, use 'default'.
    $form_arg .= '.default';
    list($entity_type, $operation) = explode('.', $form_arg);
    if ($request->attributes
      ->has($entity_type)) {
      $entity = $request->attributes
        ->get($entity_type);
    }
    else {
      $entity = $manager
        ->getStorageController($entity_type)
        ->create(array());
    }
    return $manager
      ->getFormController($entity_type, $operation)
      ->setEntity($entity);
  }

}