How to Build Rails API Authentication using JWT?

Table of Contents

Introduction

We all know how API authentication using JWT has become important while building any application. Are you stuck with your JWT authentication? Do you want to learn how to build Rails API authentication using JWT? Then this guide is for you!

Prerequisites to Build Rails API Authentication Using JWT

We will build a simple demo application implementing the Login feature and see how to implement JWT-based authentication in the Rails app. Here’s what you need.

• Ruby 2.7.0
• Postman
• Rails 7.0.3
• SQLite DB

Create Rails Application

To begin with, let’s create a Rails app by using the below command

$ rails new jwt_demo --api 

Add Gems

Now add gems to your project. Here we will need two gems:

• JWT
  • Open industry standard (RFC 7519)
  • Used to represent claims securely between two parties
• bcrypt
  • An algorithm used for password hashing

# Use JWT gem for token-based authentication
gem 'jwt'
# Use ActiveModel has_secure_password
gem 'bcrypt', '~> 3.1.7'

Now, install all dependencies by running bundle install.

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Create User Model

The next step in our tutorial is to create a user model. For that use the below command.

rails g model user name:string user_name:string email:string Password_digest:string

Run migration using rails db:migrate

Add the below code to your User Model.

Create User Controller

Now, moving on to creating a controller with the below command.

rails g controller users

Add CRUD Operations

We will be implementing CRUD operations in our application. So, for that refer to the below code.

Create JwtToken Concern

Now, in this section, we will implement JWT. As shown below we will use these two functions for creating Rails API Authentication using JWT.

Add the authenticate_user method inside your application_controller

Creating Authentication Controller

Use the below command to create an authentication controller.

rails g controller authentication

Implementing the Login Function

Now, we will implement the login function in authentication_controller as shown in the below code.

Update routes.rb

Use the code to update the route.

Test the API using Postman

So, we are done with building our demo application. It’s time to test now!

Create Users

Login

Conclusion