使用以下JSON：

{
    type: "test",
    version: 1,
    data: {
        name: "omni",
        id: "123",
        value: 3
    }
}

字符串
我尝试使用2个C++函数获取其数据：

void process_data(std::string type, std::string data)
{
        boost::json::value data = boost::json::parse(data);
        std::string name = json.at("name").as_string().c_str();
        std::string id = json.at("id").as_string().c_str();
        int value = json.at("value").as_int64();

        std::cout << "Message data content:" << std::endl;
        std::cout << "Name: " << name << std::endl;
        std::cout << "Id: " << id << std::endl;
        std::cout << "Value: " << value << std::endl;
}

void process_message(std::string payload)
{
        boost::json::value json = boost::json::parse(payload);
        std::string type = json.at("type").as_string().c_str();
        int version = json.at("version").as_int64();

        std::cout << "Message received:" << std::endl;
        std::cout << "Type: " << type << std::endl;
        std::cout << "Version: " << version << std::endl;

        std::string data = json.at("data").as_string().c_str(); !!! Getting error here
        process_data(data);
}

型
解析data时出现以下错误：

terminate called after throwing an instance of 'boost::wrapexcept<std::invalid_argument>'
  what():  not a string
Aborted (core dumped)

型
有办法解决吗？