Using post with express: I want to receive data from the user and then send that data back to the user with a new file

Question

I'm creating a node.js webpage of a tabletop card game and I originally built the application on the backend while being able to only handle one game at a time (as I only tested one at a time). Now that I'm incorporating the front end, and need the ability to process multiple games at a time, I'm struggling with how to receive a user's name and id code and either create or join a specific game while still remembering on client side who the player themselves is:

Earlier algorithm:

--Have global variable player and update to the user inputed name with post req (via express).

--send user gameView.html file

--from there (client side) const socket = io.connect(), socket.emit('newPlayer', socket.id)

--create a player object linking the socket id and global variable player

--reset the global player variable to ""

--continue waiting for the rest of the players

Obviously this is very sloppy practice and was only being used for the development of the backend. Now that I need to handle multiple users and games my algorithm (ideally) would work as such:

--User posts their name and an id code via the prePlayView.html file

--send user the gameView.html file as well as the inputted name and id (this is the part i'm not sure how to implement, as socket id changes after new file is sent so there's no way to track on server side)

--On client side, const socket = io.connect(), socket.emit('newPlayer', name, id);

--if id is blank then create game object with unique id and store in dictionary of games with key id and add player

Any ideas? am i fundamentally missing something? I'm fairly new to node.js.

Here's my current implementation for reference:

var app = express();
app.set('port', 5000);
// called when a player enters the game
app.post("/userView.html", function(req, res) {
  var body = "";
  req.on('data', function(char) {
    body += char;
  });

  req.on('end', function () {
    var playerName = body.substr(body.indexOf("=") + 1, body.indexOf("&") - 4);
    var id = body.substr(body.indexOf("&") + 4, body.length);
    body = "";
    var options = {
      headers: {
        'id': id,
        'names': playerName
      }
    }
    res.sendFile(path.join(__dirname, 'userView.html'), options);

  });

Answer 1

I'm going to assume you are using sockets to communicate between your server and client.

You're right, if you want to handle multiple games at once, you cannot use a global variable on your server to store details of the user currently registering. Using this strategy, only one player can register with the server at a time.

A better strategy would be to remember which clients have connected to the server in the past, and when they make a request, to temporarily load their information just for the duration of their request, and just in the scope of your server's express route handler.

I'm happy to introduce you to the concept of sessions . You can use them to remember information about previously connected clients. There's a middleware that adds sessions to express called express-sessions . Also, assuming you're using sockets.io, there's also an FAQ on using socket.io with express-session .

I cannot cover everything you'll have to change about your architecture here to support multiple games at once, but learning about and utilizing sessions is one possible pathway. Please take it slow, and bite off one piece at a time. Learning how to build web apps to do what you're imagining can be difficult, focusing just on one step at a time is necessary :)