Node.js API + Passport – Local Authentication Strategy

Passport is a popular authentication middleware for Node.js. It simplifies the process of handling authentication for web applications, including the use of local authentication strategies.

In this article, we will discuss how to set up a Node.js API with Passport using the local authentication strategy. We will also create an endpoint to retrieve information about the authenticated user.

Setting up the Node.js API with Passport

First, we need to install the necessary packages using npm:

		
			npm install express passport passport-local body-parser express-session
		
	

Once the packages are installed, we can set up our Node.js API. We can start by creating a basic Express server:

		
			const express = require('express');
			const passport = require('passport');
			const LocalStrategy = require('passport-local').Strategy;
			const bodyParser = require('body-parser');
			const session = require('express-session');

			const app = express();

			app.use(bodyParser.urlencoded({ extended: true }));
			app.use(session({ secret: 'secret', resave: false, saveUninitialized: false }));
			app.use(passport.initialize());
			app.use(passport.session());

			// Other middleware and routes can be added here

			app.listen(3000, () => {
			  console.log('Server is running on port 3000');
			});
		
	

Local Authentication Strategy

Next, we need to set up the local authentication strategy using Passport. This involves defining a strategy and providing functions to handle authentication and user serialization/deserialization:

		
			passport.use(new LocalStrategy(
			  function(username, password, done) {
			    // Validate the username and password
			    // Call done() with the user object if authentication is successful, or false otherwise
			  }
			));

			passport.serializeUser(function(user, done) {
			  done(null, user.id);
			});

			passport.deserializeUser(function(id, done) {
			  // Retrieve the user object from the database using the id
			  done(null, user);
			});
		
	

Authenticated User Endpoint

Finally, we can create an endpoint to retrieve information about the authenticated user. This endpoint can be protected using the middleware provided by Passport:

		
			app.get('/user', isAuthenticated, (req, res) => {
			  // Return information about the authenticated user
			});

			function isAuthenticated(req, res, next) {
			  if (req.isAuthenticated()) {
			    return next();
			  }
			  res.status(401).json({ message: 'Unauthorized' });
			}
		
	

With the endpoint in place, we can now access information about the authenticated user by making a GET request to the /user endpoint.

Conclusion

In this article, we have explored how to set up a Node.js API with Passport using the local authentication strategy. We have also created an endpoint to retrieve information about the authenticated user. Passport provides a flexible and efficient way to handle authentication in Node.js applications, making it a valuable tool for web developers.