/**
* Executes the execute method of an action.
*
* @param sfAction $actionInstance An sfAction instance
*
* @return string The view type
*/
protected function executeAction($actionInstance)
{
// execute the action
$actionInstance->preExecute();
$viewName = $actionInstance->execute($this->context->getRequest());
$actionInstance->postExecute();
return null === $viewName ? sfView::SUCCESS : $viewName;
}