MERN Authentication & Authorization with JWT: Create a Login User API in Node JS | Part 9

In this tutorial, we will be creating a login user API in Node JS for our MERN (MongoDB, Express, React, Node) authentication & authorization system using JWT (JSON Web Tokens).

Step 1: Setting up the Project

First, we need to create a new Node JS project and set up the necessary dependencies. You can do this by running the following commands in your terminal:

    
      $ mkdir mern-authentication
      $ cd mern-authentication
      $ npm init -y
      $ npm install express mongoose jsonwebtoken bcryptjs
    
  

Step 2: Creating the User Model

Next, we need to create a User model in our Node JS project. Here’s an example of how you can define the User model using Mongoose:

    
      const mongoose = require('mongoose');
      const Schema = mongoose.Schema;
      
      const userSchema = new Schema({
        email: { type: String, required: true },
        password: { type: String, required: true }
      });
      
      module.exports = mongoose.model('User', userSchema);
    
  

Step 3: Creating the Login User API

Now that we have our User model set up, we can create the API endpoint for logging in a user. Here’s an example of how you can define the login route in your Node JS project:

    
      const express = require('express');
      const router = express.Router();
      const User = require('../models/User');
      
      router.post('/login', async (req, res) => {
        const { email, password } = req.body;
        
        const user = await User.findOne({ email });
        
        if (!user) {
          return res.status(400).json({ message: 'User not found' });
        }
        
        if (user.password !== password) {
          return res.status(400).json({ message: 'Invalid password' });
        }
        
        // Generate JWT token
        // Return token to client
      });
      
      module.exports = router;
    
  

Step 4: Testing the Login User API

Finally, you can test the login user API using tools like Postman or by creating a simple frontend using React. Make sure to include appropriate error handling and validation in your API code.

That’s it for creating a login user API in Node JS for our MERN authentication & authorization system with JWT! Stay tuned for more tutorials on building a complete authentication system.