Lecture 304:- Setting up Passport.js

To set up Passport.js for authentication in your application, follow these steps:

1. Install Passport.js and other required packages using NPM:

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   npm install passport passport-local express-session bcrypt

   • passport is the core library of Passport.js.
   • passport-local is a strategy for authenticating with a username and password.
   • express-session is used to maintain user session across requests.
   • bcrypt is a library for hashing and salting passwords.

2. Import and initialize the required packages in your application:

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   const express = require('express'); const session = require('express-session'); const passport = require('passport'); const LocalStrategy = require('passport-local').Strategy; const bcrypt = require('bcrypt'); const app = express(); app.use(express.urlencoded({ extended: true })); app.use(session({  secret: 'your-secret-key',  resave: false,  saveUninitialized: false })); app.use(passport.initialize()); app.use(passport.session());

   Here, we're setting up the Express application with the following:

   • express.urlencoded() middleware for parsing request bodies.
   • express-session middleware to manage user sessions.
   • passport middleware to initialize Passport.js and configure it to use sessions.

3. Define the LocalStrategy for authenticating users with a username and password:

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   passport.use(new LocalStrategy((username, password, done) => {  User.findOne({ username: username }, (err, user) => {    if (err) { return done(err); }    if (!user) { return done(null, false); }    bcrypt.compare(password, user.password, (err, res) => {      if (res) {        return done(null, user);      } else {        return done(null, false);      }    });  }); }));

   This sets up the LocalStrategy to find the user with the provided username, compare the provided password against the hashed password stored in the database using bcrypt.compare(), and call the done callback with the authenticated user object or false.

4. Serialize and deserialize the user object to and from the session:

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   passport.serializeUser((user, done) => {  done(null, user.id); }); passport.deserializeUser((id, done) => {  User.findById(id, (err, user) => {    done(err, user);  }); });

   This defines how Passport.js should store the user object in the session and retrieve it when needed.

5. Protect the routes that require authentication using passport.authenticate():

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   app.get('/profile', requireLogin, (req, res) => {  res.render('profile', { user: req.user }); }); function requireLogin(req, res, next) {  if (req.isAuthenticated()) {    next();  } else {    res.redirect('/login');  } }

   Here, we're using the requireLogin middleware to check if the user is authenticated using req.isAuthenticated() and redirect them to the login page if they're not.