Sending JSON string to Node.JS server using Socket.IO returning nothing

Question

I have this string in JSON format (C#):

coordinatesJson = "{\"latitude\":\"" + latitude + "\",\"longitude\":\"" + longitude + "\"}";

That I send to my Node.JS server using Socket.IO as such:

socket.Emit("send coordinates", JSONObject.CreateStringObject(coordinatesJson));

On my server I have:

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);

server.listen(3000);

app.get('/', function(req, res){
res.send('Connection Successful');
});

io.on('connection', function(socket){

socket.on('client connect', function(){
    console.log("player connected");
    socket.emit("test");

});

socket.on('send coordinates', function(data){
    console.log(data);
    var data = JSON.parse(data);
    console.log(data);
    });
});

console.log('\n--- Server is running...\n');

But nothing appears. Any help?

EDIT 1: I meant if I do:

coordinatesJson = "{ 'latitude': '"+latitude+"', 'longitude': '"+longitude+"' }";

This reaches the server and outputs the proper string

Edit 2: C# Code:

using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;
using SocketIO;
using UnityEngine.UI;

public class NetworkManager : MonoBehaviour {

public SocketIOComponent socket;
public Text serverMessageDebug;

private string latitude;
private string longitude;
private string coordinatesJson;

void Start() {

    latitude = "5"; //GPS.Instance.latitude.ToString();
    longitude = "5"; //GPS.Instance.longitude.ToString();

    //coordinatesJson = "{ 'latitude': '"+latitude+"', 'longitude': '"+longitude+"' }";
    coordinatesJson = "{\"latitude\":\"" + latitude + "\",\"longitude\":\"" + longitude + "\"}";
    Debug.Log(coordinatesJson);


    EstablishConnection ();
    //Subscrible to node.js websocket events
    socket.On ("test", OnTest);

}

#region Server Connection

public void EstablishConnection(){      
    StartCoroutine (ConnectToServer ());
}

private IEnumerator ConnectToServer(){      
    yield return new WaitForSeconds (0.5f);
    socket.Emit("client connect");
    socket.Emit("send coordinates", JSONObject.CreateStringObject(coordinatesJson));
    yield return new WaitForSeconds (1f);
}

#endregion
#region Websocket Events
private void OnTest(SocketIOEvent socketIOEvent){
    Debug.Log ("This is a test from the server");
    serverMessageDebug.text = "This is a test from the server";
    }
#endregion
}

"nothing", or null or '', or an error?. Put a console.log before JSON.parse, does it reach there?, If it does, show what's data. — Marcos Casagrande
– Marcos Casagrande, Commented Apr 10, 2018 at 22:53
Nothing, as if the line was never executed. If I write the string using a combination of single quotes and double quotes as such: "{ 'latitude': '"+latitude+"', 'longitude': '"+longitude+"' }"; I actually comes through, but then when I try to parse it, it complains about the single quotes. I guess JSON isn't fond of single quotes? — David
– David, Commented Apr 10, 2018 at 22:54
Show server side code, for all we know you don't have a listener. — Marcos Casagrande
– Marcos Casagrande, Commented Apr 10, 2018 at 22:55
you can use backticks (`), but it's readable. When we see how are you setting up socket.io, and if it's even listening or running we can help you :) — Marcos Casagrande
– Marcos Casagrande, Commented Apr 10, 2018 at 23:00
So, you're saying that if you send the raw string, without JSONObject... it reaches the server? — Marcos Casagrande
– Marcos Casagrande, Commented Apr 10, 2018 at 23:01

DeadDreams · Accepted Answer · 2021-10-30 10:09:22Z

1

this should work. first create a class like this:

[Serializable]
public class CoordinatesJSON
{
    public double[] Coordinates;

    public CoordinatesJSON(double latitude, double longitude)
    {
        Coordinates = new double[] { latitude, longitude };
    }
}

then make a jsonObject method like this:

JSONObject ConvertDataToJson()
{
    double lat = GPS.latitude;
    double lon = GPS.longitude;

    string data = JsonUtility.ToJson(new CoordinatesJSON(lat, lon));
    return new JSONObject(data);
}

and send data to Server like this:

public void SendGPSCoordinateToServer()
{
    
    socket.Emit("send coordinates", ConvertDataToJson());
}

and serve side:

socket.on('send coordinates', function(data){

    console.log('Json Data: '+JSON.stringify(data));
    console.log('Data: ' + data.Coordinates);

});

edited Oct 30, 2021 at 10:09

answered Oct 30, 2021 at 9:56

DeadDreams

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