C++ json deserializer [closed]

Question

We can C++ project and we need to (de) serialize objects from and into json.

In C# we are using JSON.NET. We simple call:

string json = JsonConvert.SerializeObject(product);
var myNewObject = JsonConvert.DeserializeObject<MyClass>(json);

Very simple and useful.

Does anybody know about free C++ library, which can be used in the same simple way like in C#?

We are using JsonCpp, but it does not support it.

Thanks very much Regards

Answer 1

C++ does not support reflection so you necessarily have to write your own serialize and deserialize functions for each object.

Answer 2

I'm using https://github.com/nlohmann/json in a C++ websocket server talking to a html/javascript client. The websocket framework is https://github.com/zaphoyd/websocketpp. So sending the json structure 'matches' from the server goes like

msg->set_payload(matches.dump());
m_server.send(hdl, msg);

And like wise from the client

var m = "la_liga";
var msg = {
    "type": "request",
    "data": m
}
msg = JSON.stringify(msg);
ws.send(msg);

When I receive json on the server I parse it and then a try-catch

void on_message(connection_hdl hdl, server::message_ptr msg) {
    connection_ptr con = m_server.get_con_from_hdl(hdl);

    nlohmann::json jdata;

    std::string payload = msg->get_payload();
    try {
        jdata.clear();
        jdata = nlohmann::json::parse(payload);
        if (jdata["type"] == "update") {
            <do something with this json structure>
        }
    } catch (const std::exception& e) {
        msg->set_payload("Unable to parse json");
        m_server.send(hdl, msg);
        std::cerr << "Unable to parse json: " << e.what() << std::endl;
    }
}

And likewise on the client

ws.onmessage = function (e) {
    var receivedMsg = JSON.parse(e.data);

    if (receivedMsg.type == "table") {
        <sort and display updated table standing>
    }
}

Websocketpp requires boost libraries.