how to get a response in realtime in Nodejs - node.js

Question

Hi I am trying to make a request and receive just the response in realtime using socketIO
and currently I am able to connect to the router but not getting any response as the error shows
Error: io is not defined.
If anyone can please help me to resolve this issue.
Below is the necessary code.
ChatPageProvider.dart
Future<void> addProduct(String message) async {
Map<String, String> headers = {
"Content-Type": "charset=utf-8",
"Content-type": "application/json"
};
const url = 'http://localhost:8080/message/check';
try {
var response = await http.post(url,
headers: headers,
body: json.encode({
"text": message,
}));
socketIO.init();
//Subscribe to an event to listen to
socketIO.subscribe('message', (jsonData) {
//Convert the JSON data received into a Map
Map<String, dynamic> data = json.decode(jsonData);
messages.add(data['message']);
notifyListeners();
});
socketIO.connect();
// final getMessage = Message(
// text: json.decode(response.body)['message'],
// );
print(response.statusCode);
notifyListeners();
} catch (error) {
throw error;
}
}
index.js
const express = require('express');
const app = express();
const notificationdetails = require('../nodePractice/router/notification');
const http = require('http').createServer(app);
const io = require('socket.io')(http);
bodyParser = require('body-parser');
var port = process.env.PORT || 8080;
app.use(bodyParser.json({limit: "50mb"}));
app.use(bodyParser.urlencoded({limit:"50mb",extended:true}));
io.on("connection",(userSocket) => {
console.log('Conntected to port')
io.emit('connected', 80);
})
var server = http.listen(port, ()=> {
console.log('listening on port' + port)
})
app.use(notificationdetails);
notification.js
const express = require('express');
const router = new express.Router()
router.post('/message/check',async(req,res) => {
console.log("Success"); // I am able to get till here but then the error occurs
io.emit("message", req.body)
try {
res.status(201).send();
io.emit("message", req.body)
}catch(e) {
res.status(401);
io.emit("message", req.body)
res.send(e);
}
})
module.exports = router
error
(node:78214) UnhandledPromiseRejectionWarning: ReferenceError: io is not defined

Answer 1

You can create a file like below, give it a name socket-io.js.
var io = require('socket.io')(9999);
module.exports = io;
Then import it first in your index.js like below snippet.
let io = require('./app/utilities/socket-io');
io.on('connection', function (socket) {
...
});
Last, you can import the same file in your notification.js file as well & try below code.
const express = require('express');
const router = new express.Router()
let io = require('./app/utilities/socket-io');
router.post('/message/check',async(req,res) => {
console.log("Success"); // I am able to get till here but then the error occurs
io.emit("message", req.body)
try {
res.status(201).send();
io.emit("message", req.body)
}catch(e) {
res.status(401);
io.emit("message", req.body)
res.send(e);
}
})
module.exports = router