public function actionCategorias()
 {
     // Parse the PUT parameters. This didn't work: parse_str(file_get_contents('php://input'), $put_vars);
     $json = file_get_contents('php://input');
     //$GLOBALS['HTTP_RAW_POST_DATA'] is not preferred: http://www.php.net/manual/en/ini.core.php#ini.always-populate-raw-post-data
     $post = CJSON::decode($json, false);
     //true means use associative array
     switch ($post->operacion) {
         case 'listado':
             $this->_articulo = ApiHelper::listadoCategorias();
             break;
         case 'listadodetalle':
             $this->_articulo = ApiHelper::listadoDetalleCategorias();
             break;
         default:
             // Model not implemented error
             $this->_sendResponse(501, sprintf('Error: Mode <b>list</b> is not implemented for model <b>%s</b>', $post->operacion));
             Yii::app()->end();
     }
     // Did we get some results?
     if (empty($this->_articulo)) {
         // No
         $this->_sendResponse(200, sprintf('No items where found for model <b>%s</b>', $post->operacion));
     } else {
         // Send the response
         $this->_sendResponse(200, CJSON::encode($this->_articulo));
     }
 }