Implementing Login Functionality in Rails

In Rails, you can easily implement login functionality using a gem called devise.

Initial Setup for Devise

Add the following to your Gemfile:

gem 'devise'

Then run bundle install.

Next, execute rails g devise:install to generate the necessary initial setup and files for devise.

Creating the User Model

Create a user model to represent members:

$ rails g devise user

When you run rails g devise <model_name>, routing settings for devise are automatically added.

Creating the Users Table

By running rails g devise user, a migration file for devise is also created. Check the migration file to confirm the table structure.

Creating Views

Next, generate the views. Simply run:

$ rails g devise:views

This completes the basic setup for devise. No controller was created because the routing for devise passes processing to the controllers within the gem.

Adding Columns to Devise

Let’s try adding a name column to devise.

$ rails g migration AddNameToUsers name:string
$ rake db:migrate

Add name to devise’s strong parameters. Devise has a method called configure_permitted_parameters for setting strong parameters, so add it there.

<!-- app/controllers/application_controller.rb -->

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  # Execute the method defined below with before_action
  before_action :configure_permitted_parameters, if: :devise_controller?

  # Assign the array [:name] to the variable PERMISSIBLE_ATTRIBUTES
  PERMISSIBLE_ATTRIBUTES = %i(name)

  protected

    # Define a method to add columns to devise’s strong parameters
    def configure_permitted_parameters
      devise_parameter_sanitizer.permit(:sign_up, keys: PERMISSIBLE_ATTRIBUTES)
      devise_parameter_sanitizer.permit(:account_update, keys: PERMISSIBLE_ATTRIBUTES)
    end

configure_permitted_parameters is triggered only for devise controllers by adding if: :devise_controller? to before_action.

Adding a Name Input Field to the Registration Screen

<!-- app/views/devise/registrations/new.html.erb -->

<div class="field">
  <%= f.email_field :email, autofocus: true, class: "form-control", placeholder: "Email Address" %>
</div>

<!-- Add a field for name input -->
<div class="field">
  <%= f.text_field :name, class: "form-control", placeholder: "Name" %>
</div>

<div class="field">
  <%= f.password_field :password, autocomplete: "off", class: "form-control", placeholder: "Password" %>
</div>

Adding a Name Edit Field to the Edit Screen

<!-- app/views/devise/registrations/edit.html.erb -->

<div class="field">
  <%= f.label :email %><br />
  <%= f.email_field :email, autofocus: true, class: "form-control" %>
</div>

<!-- Add a field for name input -->
<div class="field">
  <%= f.label :name %><br />
  <%= f.text_field :name, class: "form-control" %>
</div>

<% if  devise_mapping.confirmable? && resource.pending_reconfirmation? %>
  <div>Currently waiting confirmation for: <%= resource.unconfirmed_email %></div>
<% end  %>

For Heroku Users

If you’re using Heroku, additional configuration is required. Enable config.secret_key in config/initializers/devise.rb.