Managing Sessions in Express.js with express-session

Managing user sessions is a fundamental aspect of web development, especially when dealing with authentication and user state management. In this guide, we'll explore how to use express-session in an Express.js application to store and retrieve session data.

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1. What is express-session?

express-session is a middleware for Express.js that enables session management by storing session data on the server-side. This is useful for tracking user activities, authentication, and managing temporary data between requests.

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2. Installing express-session

To get started, install the express-session package using npm:

bash

npm i express-session

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3. Configuring express-session in Your App

First, require express-session in your main application file (e.g., app.js) and configure it as middleware:

javascript

const express = require('express');
const session = require('express-session');

const app = express();

// Configure session middleware
app.use(session({
    secret: "gggggghhhhhh", // Secret key for signing the session ID
    resave: false, // Prevents resaving session if nothing has changed
    saveUninitialized: false // Prevents saving uninitialized sessions
}));

app.use(express.json());

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4. Setting and Retrieving Session Data in Routes

Now, let's create a route file (routes/sessionRoutes.js) to set and retrieve session values.

Setting Session Data

In the following route, we set session variables:

javascript

const express = require('express');
const router = express.Router();

router.get('/', (req, res) => {
    req.session.name = "hello";
    req.session.ban = true;
    res.send("Session data set.");
});

Retrieving Session Data

To access and check session data, we create another route:

javascript

router.get('/sessions', (req, res) => {
    console.log(req.session); // Logs session data to the console
    res.send(`Session Data: ${JSON.stringify(req.session)}`);
});

module.exports = router;

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5. Integrating Routes in the App

Now, include these session routes in your main application (app.js):

javascript

const sessionRoutes = require('./routes/sessionRoutes');
app.use('/session', sessionRoutes);

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6. Running the Application

Run the application using:

bash

node app.js

Testing the Endpoints

1. Set session data:
   Open your browser or use Postman and visit:

   bash
   
   http://localhost:3000/session/
   

   This will set session values.

2. Retrieve session data:
   Visit:

   bash
   
   http://localhost:3000/session/sessions
   

   This will display the stored session data.