protected function _mongo($id,$pw,$realm) {
		$success = (bool)
			$this->mapper->load(
				[$this->args['id']=>$id]+
				($this->func?[]:[$this->args['pw']=>$pw])+
				(isset($this->args['realm'])?
					[$this->args['realm']=>$realm]:[])
			);
		if ($success && $this->func)
			$success = call_user_func($this->func,$pw,$this->mapper->get($this->args['pw']));
		return $success;
	}