[RUBY] Create authentication function in Rails application using devise


--devise is a gem that allows you to easily add authentication to your Rails application. devise is a wrapper for Rack middleware called warden, and the actual authentication is done by warden (so if you want to know the implementation details, first implement warden. I think I need to see it). --In the Rails tutorial, the authentication function is created by scratching, but in the actual Rails application, it seems that creating the authentication function using this devise is the de facto standard.

――This time, for my own study, I would like to organize how to use devise to add authentication function to Rails application. The content is almost the same as this article. Xie Xie

--All of the following implementations can be found in this repository.


install devise

1. Edit Gemfile

# Devise
gem 'devise'

2.bundle install

$bundle install

devise settings

1. Execute the following command

$ rails g devise:install
      create  config/initializers/devise.rb
      create  config/locales/devise.en.yml

Depending on your application's configuration some manual setup may be required:

  1. Ensure you have defined default url options in your environments files. Here
     is an example of default_url_options appropriate for a development environment
     in config/environments/development.rb:

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

     In production, :host should be set to the actual host of your application.

     * Required for all applications. *

  2. Ensure you have defined root_url to *something* in your config/routes.rb.
     For example:

       root to: "home#index"
     * Not required for API-only Applications *

  3. Ensure you have flash messages in app/views/layouts/application.html.erb.
     For example:

       <p class="notice"><%= notice %></p>
       <p class="alert"><%= alert %></p>

     * Not required for API-only Applications *

  4. You can copy Devise views (for customization) to your app by running:

       rails g devise:views
     * Not required *


Set default URL


Rails.application.configure do
  config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }

Create root page

You can skip this and set any page as the root page.

$rails g controller StaticPages index


Rails.application.routes.draw do
  root 'static_pages#index'
  # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html

Set flash message

Edit app / views / layouts / application.html.erb

<!DOCTYPE html>
  <%= csrf_meta_tags %>

  <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
  <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>
  <p class="notice"><%= notice %></p>
  <p class="alert"><%= alert %></p>

  <%= yield %>


Create a devise view

$ rails g devise:views
invoke  Devise::Generators::SharedViewsGenerator
create    app/views/devise/shared
create    app/views/devise/shared/_error_messages.html.erb
create    app/views/devise/shared/_links.html.erb
invoke  form_for
create    app/views/devise/confirmations
create    app/views/devise/confirmations/new.html.erb
create    app/views/devise/passwords
create    app/views/devise/passwords/edit.html.erb
create    app/views/devise/passwords/new.html.erb
create    app/views/devise/registrations
create    app/views/devise/registrations/edit.html.erb
create    app/views/devise/registrations/new.html.erb
create    app/views/devise/sessions
create    app/views/devise/sessions/new.html.erb
create    app/views/devise/unlocks
create    app/views/devise/unlocks/new.html.erb
invoke  erb
create    app/views/devise/mailer
create    app/views/devise/mailer/confirmation_instructions.html.erb
create    app/views/devise/mailer/email_changed.html.erb
create    app/views/devise/mailer/password_change.html.erb
create    app/views/devise/mailer/reset_password_instructions.html.erb
create    app/views/devise/mailer/unlock_instructions.html.erb

Create User model

rails g devise User

The above command will generate the following migration files.


# frozen_string_literal: true

class DeviseCreateUsers < ActiveRecord::Migration[5.2]
  def change
    create_table :users do |t|
      ## Database authenticatable
      t.string :email,              null: false, default: ""
      t.string :encrypted_password, null: false, default: ""

      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at

      ## Rememberable
      t.datetime :remember_created_at

      ## Trackable
      # t.integer  :sign_in_count, default: 0, null: false
      # t.datetime :current_sign_in_at
      # t.datetime :last_sign_in_at
      # t.inet     :current_sign_in_ip
      # t.inet     :last_sign_in_ip

      ## Confirmable
      # t.string   :confirmation_token
      # t.datetime :confirmed_at
      # t.datetime :confirmation_sent_at
      # t.string   :unconfirmed_email # Only if using reconfirmable

      ## Lockable
      # t.integer  :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
      # t.string   :unlock_token # Only if unlock strategy is :email or :both
      # t.datetime :locked_at

      t.timestamps null: false

    add_index :users, :email,                unique: true
    add_index :users, :reset_password_token, unique: true
    # add_index :users, :confirmation_token,   unique: true
    # add_index :users, :unlock_token,         unique: true

It seems that database_authenticatable, registerable, recoverable, rememberable and validatable are turned on by default.


class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable

This time, we will create it with the default, but you can optionally enable any of the 10 modules.

module   Overview                                                       
Database Authenticatable Hash the password and store it in the database to verify the authenticity of the user during sign-in. Authentication can be done with both POST request or HTTP basic authentication.
Omniauthable OmniAuth(https://github.com/omniauth/omniauth)Add support.
Confirmable Send an email with verification instructions to see if your account has already been verified at sign-in.
Recoverable Resets the user's password and sends a reset instruction.
Registerable Process user sign-up through the registration process, allowing users to edit and destroy their account.
Rememberable Manages the generation and clearing of tokens to remember users from stored cookies.
Trackable Keep track of sign-ins, time stamps, and IP addresses..
Timeoutable Expires sessions that have been inactive for the specified time period.
Validatable Provides email and password verification. This is optional and customizable so you can define your own validation.
Lockable Locks the account after the specified number of failed sign-in attempts. Can be unlocked by email or after a specified time period

Perform a migration

$ rake db:migrate

Edit View

Add header


<!DOCTYPE html>
  <%= csrf_meta_tags %>

  <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
  <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>
        <% if user_signed_in? %>
        <%= link_to 'Profile change', edit_user_registration_path %>
        <%= link_to 'Log out', destroy_user_session_path, method: :delete %>
    <% else %>
        <%= link_to 'Sign up', new_user_registration_path %>
        <%= link_to 'Login', new_user_session_path %>
        <% end %>
  <p class="notice"><%= notice %></p>
  <p class="alert"><%= alert %></p>

  <%= yield %>


――When you access the top page, a screen like this is generated. スクリーンショット 2020-06-23 3.48.36.png

--Click sign up スクリーンショット 2020-06-23 3.34.51.png

――When you signed up and entered your email address and password, you were able to log in successfully! スクリーンショット 2020-06-23 3.35.29.png


Helper methods provided by devise


You can check if the user is logged in.


You can access the logged-in user.


You can access the session.

Change redirect destination after signing up


class ApplicationController < ActionController::Base
  def after_sign_up_path_for(resource)
    edit_user_registration_path #You can edit here and jump to any page

After signing up, I am now redirected to the following page.

スクリーンショット 2020-06-23 3.34.18.png

Change redirect destination after login


class ApplicationController < ActionController::Base
  def after_sign_in_path_for(resource)
    edit_user_registration_path #You can edit here and jump to any page

Callback function

(I'm not sure exactly here)

--It seems that after_fetch is the only callback that devise calls (citation needed), so if you want to call other callbacks, use warden interface. Must be called directly.


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