Store Socket IO socket.id in Express session - express

Question

I have a web app using Angular and Express. I have a rest api for database updates and I am also using SocketIO to update the clients in realtime.
I am tracking a list of active socket IDs for each user but now I would like to have access to the clients socket id in my express route so that I can emit a message to all other users (equivalent of socket.broadcast)
I'm trying to store the socket ID in an expression session so I can access it in my route but i've not been able to get it working. In the code below i'm logging my session when the socket connects and this shows the socketio key i've added but in the /jobs request the socketio key is undefined..
My server.ts is something like this:
import * as expsession from 'express-session'
// create Express app variable
const app = express()
// create HTTP server
const server = http.createServer(app);
// set up CORS so it can work Angular application at another domain/port
app.use(cors({
origin: [ "http://localhost:4200" ],
credentials: true
}))
// install session middleware
const session = expsession({
secret: 'random secret',
saveUninitialized: true,
resave: true,
cookie: { secure: false }
});
// run session middleware for regular http connections
app.use(session);
// *** SOCKET IO *** //
const io = require('socket.io')(server);
// run session middleware for socket.io connections
io.use((socket, next) => {
session(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', (socket) => {
console.log(`socket.io connected: ${socket.id}`);
// save socket.io socket in the session
socket.request.session.socketio = socket.id;
socket.request.session.save();
console.log("socket.io connection, session:\n", socket.request.session);
});
app.get('/jobs', (req, res) => {
const session = req.session;
console.log("JOBS: session at '/jobs':\n", session);
Job.getJobs((err, jobs) => {
if (err) {
res.json({success: false, msg: err});
} else {
res.json(jobs);
}
});
});
I'm also including credentials in my angular service request, e.g.:
this.http.get(api_url + '/jobs', {withCredentials:true}).subscribe((jobs:IJob[]) => {
this.jobs$.next(jobs)
})

Answer 1

When a socket is connected an id is created(socket.id) and by default it joins to a room with that id. If you already have id for your client just send it to the server and join to a room with the client id.
socket.leave(socket.id);//leaving default room
socket.join(my_custom_id);//joining to custom id room
the custom id will appear in client side as the websocket7 id.
If you still don't know how to get the id in your express route; use a jsonwebtoken with the id and decoded in your route, thats it.
Example:
var bearer = req.headers.authorization.split(" ")[1];//this is node, get headers with express way
var auth_data = jwt.decodeToken( bearer );
decoding:
var jwt = require('jsonwebtoken');
var secret = 'your_secret';
function decodeToken(token){
try {
var decoded = jwt.verify( token , secret );
return decoded;
} catch (error) {
console.log('jwt', error);
return null;
}
}
encoding:
//data is an object with data you want to encode, id, etc
function createJsonWebToken(data){
var token = jwt.sign( data, secret );
return token
}
/*after encoding you send this token to the
client, then you send it back to the server
to the routes you need the data, then just
decoded it in that route*/