在 express 中使用套接字时出现问题

Question

I have a problem with the socket in my program. export the "io" connection and although I can broadcast from any part of the normal program (just by referring to "io"), I cannot use "socket" and broadcast with it unless it is within the same connection of "io." I would like to know how to use socket from any other part of the program, with functions such as "socket.emit ()" or "socket.broadcast.emit" etc. Or how to call this one.

This is my index.js:

 const express = require('express'); const restApi = express(); const cors = require('cors'); const server = require('http').createServer(restApi); const rutas = require('./src/routes/Routes.js'); const io = require('./src/socket/SocketManager.js'); io.attach(server); restApi.use(express.json()); restApi.use(express.static('public')); restApi.use(cors()); restApi.options('*', cors()); server.listen(4040, () => console.log('Listening server in port 4040')); restApi.all('/*', function(req, res, next) { res.header("Access-Control-Allow-Origin", "*"); res.header("Access-Control-Allow-Headers", "X-Requested-With"); next(); }); restApi.use('/api',rutas);

my managersocket.js:

 const io = require('socket.io')(); io.on('connection', function (socket) { console.log('NUEVA CONEXION: ',socket.id); socket.emit('recoger',socket.id); }); module.exports = io;

This is where I would like to use the socket or at least call the function.

and User.js:

 var io = require('../../socket/SocketManager'); var RouterUser = function(){ this.practicafuncion = function (req,res){ res.header("Access-Control-Allow-Origin", "*"); res.header("Access-Control-Allow-Headers", "X-Requested-With"); console.log('probando entrar por rest y que salga un mensaje por socket'); res.send({ status:'Aprobado', msj:'Enviado por rest' }); //this works correctly. io.sockets.emit('mensaje','**MENSAJESERVIDORPORSOCKET**'); //This is not the problem when using "socket". socket.broadcast.emit('mensaje','**MENSAJESERVIDORPORSOCKET**'); }; } module.exports = function(){ var instancia = new RouterUser(); return instancia; };

same is the repository where the whole code is

https://github.com/proxirv/Socket.io-router

Answer 1

socket is a temporary object that exists only for the duration of one particular client connection. And, there can be zillions of them (one or more for each connected client). As such, you don't just export one socket or stuff it in a global and try to use that everywhere.

So, if what you're trying to do is to access the socket.io connection for the user that you just received an http request for, that's a bit more complicated and there are several different ways to approach it.

One approach, I've used before is shown below:

const express = require('express');
const app = express();
const server = app.listen(80);
const io = require('socket.io')(server);
const expsession = require('express-session');
const path = require('path');

// install session middleware
const sessionMiddleware = expsession({
  secret: 'random secret',
  saveUninitialized: true,
  resave: true
});

// run session middleware for regular http connections
app.use(sessionMiddleware);

// run session middleware for socket.io connections
io.use(function(socket, next) {
    sessionMiddleware(socket.request, socket.request.res, next);
});

// when a socket.io connection connects, put the socket.id into the session
// so it can be accessed from other http requests from that client    
io.on('connection', function(socket) {
    // socket.handshake.headers
    console.log(`socket.io connected: ${socket.id}`);

    // save socket.io socket in the session
    console.log("session at socket.io connection:\n", socket.request.session);
    socket.request.session.socketio = socket.id;
    socket.request.session.save();
});

// any arbitrary express route definition
// Note: you can't send socket.io data in a request that loads an HTML page
//       because that client hasn't yet established the socket.io connection
//       for that page.  The socket.io connections will be created after
//       the browser loads this page.
app.get("/", function(req, res) {
    const session = req.session;
    console.log("\n\npage load\n---------------------------\n");
    console.log("session:\n", session);
    res.sendFile(path.join(__dirname, "socket-io-session.html"));
});

// Upon an API call from a page that already has a socket.io connection,
// respond to the API call and send something to that page's socket.io socket
app.get("/api/test", function(req, res) {
    const session = req.session;
    io.sockets.connected[session.socketio].emit('show', "sending some data");
    console.log("session:\n", session);
    console.log("session.socketio:\n", session.socketio);
    res.json({greeting: "hello"});
});

Here are the steps in that concept:

1. Set up express-session for regular http connections. This gives you a place to store stuff that belongs to one particular client (keyed by a cookie)
2. Set up express-session for the socket.io connection so you can also have access to express-session data in socket.io connections.
3. When a socket.io connection happens, store the socket.id in the sesssion. This makes the socket.id available for future http requests from that specific client
4. When some future http request comes in from that client, you can reach into the session, get the socket.id value (which is just a string) and then use that to get the socket for that user and once you have the socket, you can use socket.emit() to send data just to that user.

---

If you didn't have other reasons for using express-session, you could also just put the socket.id into a cookie all by itself when the socket.io connection connects and then get the socket.id from the cookie during your http request.