Updating the Backend Automatically in Express.js When the Database Changes

Question

Updating the Backend Automatically in Express.js When the Database Changes

I decided to create a chat platform from scratch to dive into the world of requests and server-side logic.

My strategy involved setting up an express.js server that listens for POST requests to '/messageReceiver'.

app.post("/messageReceiver", (req, res) => {
        logMessage(req.body.message);
});

Next, I developed a 'client' capable of sending data to this designated endpoint:

var XMLHttpRequest = require("XMLHttpRequest").XMLHttpRequest;

function makePostRequest(url, json)
{
        let http = new XMLHttpRequest();
        http.open("POST", url, true);
        http.setRequestHeader("Content-Type", "application/json");
        http.send(JSON.stringify(json));
}

function sendMessage(url, message)
{
    makePostRequest(url, {message: message});
    logMessage(message);
}

All seems well so far. However, my current challenge is figuring out how to refresh the main page upon receiving a post request in order to display the latest messages.

app.get('/', (req, res) => {
        res.render('index', data = retrieveMessages());
});

I've experimented with various methods found online, such as:

res.redirect('back');
res.redirect(req.get('referer'));
res.redirect(req.originalUrl)

While res.redirect('back') worked before, my predicament lies in refreshing a visitor's connection based on another user's actions without direct access to their response object. It's proven challenging to find a solution for reloading pages externally.

(I acknowledge there are simpler ways to build a chat site rather than engaging in back-and-forth data exchanges between servers)

javascript arrays express

Answer 1

Answer №1

If you're looking to establish real-time communication between a server and client, consider utilizing the socket.io package. With Socket.io, you can conveniently send requests from the server to the client once there's data available.

Here's an example to guide you:

Server Side:

// Setting up express
const express = require('express');
const app = express();
// Creating the server
const http = require('http');
const server = http.createServer(app);
// Implementing socket.io
const io = require('socket.io')(server);
// Specifying the port for server listening
let port = 3000;

function logMessage(message, id) {
    ...
    io.emit('message_sent_' + id, { message }); // Notifying clients about the message sent
}
function receiveMessages(id) {
    // Retrieving messages
}

app.post('/messageReceiver', (req, res) => {
    // req.body.message contains the message while req.cookies.id represents the client's random ID
    logMessage(req.body.message, req.cookies.id);
});

app.get('/', (req, res) => {
    res.cookie('id', 'some-generated-id'); // Assigning a unique ID as a cookie for fetching user messages
    res.render('index', { data: retrieveMessages() });
});

// Configuring the server to listen for incoming requests
server.listen(port, () => console.log('My app is online');

Client Side:

<!doctype html>
<html>
<body>
    ...
</body>
<script src="/socket.io/socket.io.js"></script>
<script>
    const socket = io.connect();
    socket.on('message_sent_' + 'some-id', function(data) {
        // Processing the received data
    });
</script>
</html>

For further information, you may refer to the following resources:

Socket.io Documentation
Express.js Official Website
Chat App with Socket.io and Express Using Node.js

Answer 2

If you're looking to establish real-time communication between a server and client, consider utilizing the socket.io package. With Socket.io, you can conveniently send requests from the server to the client once there's data available.

Here's an example to guide you:

Server Side:

// Setting up express
const express = require('express');
const app = express();
// Creating the server
const http = require('http');
const server = http.createServer(app);
// Implementing socket.io
const io = require('socket.io')(server);
// Specifying the port for server listening
let port = 3000;

function logMessage(message, id) {
    ...
    io.emit('message_sent_' + id, { message }); // Notifying clients about the message sent
}
function receiveMessages(id) {
    // Retrieving messages
}

app.post('/messageReceiver', (req, res) => {
    // req.body.message contains the message while req.cookies.id represents the client's random ID
    logMessage(req.body.message, req.cookies.id);
});

app.get('/', (req, res) => {
    res.cookie('id', 'some-generated-id'); // Assigning a unique ID as a cookie for fetching user messages
    res.render('index', { data: retrieveMessages() });
});

// Configuring the server to listen for incoming requests
server.listen(port, () => console.log('My app is online');

Client Side:

<!doctype html>
<html>
<body>
    ...
</body>
<script src="/socket.io/socket.io.js"></script>
<script>
    const socket = io.connect();
    socket.on('message_sent_' + 'some-id', function(data) {
        // Processing the received data
    });
</script>
</html>

For further information, you may refer to the following resources:

Socket.io Documentation
Express.js Official Website
Chat App with Socket.io and Express Using Node.js

Updating the Backend Automatically in Express.js When the Database Changes

Answer №1

Here's an example to guide you:

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