code: public function renderJSON(MvcEvent $event)
      {
          if (!$this->hasRunned) {
              $valueToPlainStati = array(1 => 'error', 2 => 'error', 3 => 'error', 4 => 'error', 5 => 'success', 6 => 'info', 7 => 'info');
              $viewModel = $event->getViewModel();
              if ($viewModel instanceof JsonModel) {
                  if (!empty($this->notifications)) {
                      $jsonNotifications = $viewModel->getVariable('notifications', array());
                      foreach ($this->notifications as $notification) {
                          $status = 'info';
                          if (array_key_exists($notification->getPriority(), $valueToPlainStati)) {
                              $status = $valueToPlainStati[$notification->getPriority()];
                          }
                          $jsonNotifications[] = array(
                              'text' => $notification->getNotification(),
                              'status' => $status
                          );
                      }
                      $viewModel->setVariable('notifications', $jsonNotifications);
                  }
                  $this->hasRunned = true;
              }
          }
          return;
      }
docs: Special handling json
  @param MvcEvent $event