Introduction: Devise is a popular and flexible authentication gem for Ruby on Rails applications. It provides a full suite of authentication features, including user registration, password recovery, and sign-in/sign-out functionality. In this tutorial, we will walk through the process of installing and configuring Devise in a Rails 7 application.

Prerequisites:

• Ruby 3.0 or newer

• Rails 7.0 or newer

• PostgreSQL 14 or newer

Step 1: Create a new Rails application Create a new Rails application by running the following command:

rails new my_app --database=postgresql

Change your working directory to the newly created application:

cd my_app

Step 2: Add Devise to your Gemfile Add the Devise gem to your Gemfile:

gem 'devise'

Then, run the bundle install command to install the gem:

bundle install

Step 3: Run Devise generator Run the following command to generate the Devise configuration files:

rails generate devise:install

This command will create an initializer file, config/initializers/devise.rb, and a set of locale files for internationalization support.

Step 4: Configure Devise settings Edit the config/initializers/devise.rb file and set the config.mailer_sender to an appropriate email address for your application:

config.mailer_sender = 'noreply@example.com'

In config/environments/development.rb, add the following line to configure the default URL options for the Devise mailer:

config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }

Step 5: Generate a User model with Devise Run the following command to generate a User model with Devise:

rails generate devise User

This will create a User model and migration file, as well as views and controllers for authentication.

Step 6: Run migrations Run the following command to apply the generated migration:

rails db:migrate

Step 7: Add Devise views and routes Run the following command to generate Devise views:

rails generate devise:views

In config/routes.rb, add the following line to define Devise routes for the User model:

devise_for :users

Step 8: Add authentication to your controllers To require authentication for specific controllers, add the following line at the beginning of the controller:

before_action :authenticate_user!

Step 9: Add navigation links In your application layout (app/views/layouts/application.html.erb), add links for user authentication:

<% if user_signed_in? %>
  <%= link_to 'Edit profile', edit_user_registration_path %> |
  <%= link_to 'Logout', destroy_user_session_path, method: :delete %>
<% else %>
  <%= link_to 'Sign up', new_user_registration_path %> |
  <%= link_to 'Login', new_user_session_path %>
<% end %>

Step 10: Test your application Start your Rails server:

rails server

Visit http://localhost:3000/users/sign_up in your browser to create a new user and test the authentication functionality.

Conclusion: You have now successfully installed and configured Devise in your Rails 7 application. With the provided code samples and instructions, you can easily integrate user authentication into your app and customize the authentication process to suit your needs.