protected function isValid()
    {
        if (!$this->request->ajax()) {
            return false;
        }
        $search = $this->request->input('search');
        if (!is_string($search) or strlen($this->request->input('search')) <= 0) {
            return false;
        }
        $token = $this->request->header('search-protection');
        if (!$this->validateToken($token)) {
            return false;
        }
        return true;
    }