Adding Devise + OmniAuth to Rails 4 App

RailsAuthSetupGuide

### This Guide is summary of steps outlined in the guide published by
### DigitalOcean here:  https://www.digitalocean.com/community/tutorials/how-to-configure-devise-and-omniauth-for-your-rails-application

### TODO:  automate this guide into a ruby script 
### TODO:  required auth tokens to be read from a local 'keys' folder w/individual
###         PROVIDER (Twitter, FB, GH, Goog, etc.) token json files


X ----- [1] Add to Gemfile
gem 'therubyracer'
gem 'devise'
gem 'omniauth'
gem 'omniauth-twitter'

$> bundle install



X ----- [2] Set Up Devise

### Generate the necessary models needed by Devise
rails generate devise:install
rails generate devise User
rake db:migrate

### Add user authorization to all pages by adding to 
### Add to $APPROOT/app/controllers/application_controller.rb :
class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_action :authenticate_user! 		#===> added this line
end



X ----- [3] Update User Model to Support OmniAuth
rails g migration AddColumnsToUsers provider uid
rake db:migrate



X ----- [4] Get the Client ID and Client Secret from the OAuth Service Provider

### You will be asked for a callback URL during the registration process.### There is a separate callback URL for each provider. Here are the 
### 	callback URLs for a few popular service providers:

	* Facebook: http://localhost:3000/users/auth/facebook/callback
	* Amazon: http://localhost:3000/users/auth/amazon/callback
	* Twitter: http://localhost:3000/users/auth/twitter/callback
	* Google: http://localhost:3000/users/auth/google/callback



X ----- [5] Update the Devise Initializer

### Now that you have the App credentials (CLIENT_ID and CLIENT_SECRET),
### 	we need to configure Devise with these credentials.

### ==> edit $APPROOT/config/initializers/devise.rb (add App credentials)
### After editing, your file looks something like this (minus comments):

Devise.setup do |config|
  #Replace example.com with your own domain name
  config.mailer_sender = '[email protected]'

  require 'devise/orm/active_record'
  config.case_insensitive_keys = [ :email ]
  config.strip_whitespace_keys = [ :email ]
  config.skip_session_storage = [:http_auth]
  config.stretches = Rails.env.test? ? 1 : 10
  config.reconfirmable = true
  config.expire_all_remember_me_on_sign_out = true
  config.password_length = 8..128
  config.reset_password_within = 6.hours
  config.sign_out_via = :delete

  #Add your ID and secret here
  #ID first, secret second
  config.omniauth :digitalocean, "db381dc9990be7e3bc42503d0", "5b0824c2722b65d29965f1a1df"
end



X ----- [6] Update the USER Model
### ==> Do two things here:
### ==> (1) adding three items to the existing list (:omniauthable, 
		:omniauth_providers => [:digitalocean], and don't forget the extra comma!)

### ==> (2) create a new method named from_omniauth to extract the 
		information that is available after the authentication.

### ==> the model USER should now look as follows:
class User < ActiveRecord::Base
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
     :omniauthable, :omniauth_providers => [:digitalocean]

  def self.from_omniauth(auth)
      where(provider: auth.provider, uid: auth.uid).first_or_create do |user|
        user.provider = auth.provider
        user.uid = auth.uid
        user.email = auth.info.email
        user.password = Devise.friendly_token[0,20]
      end
  end
end



----- [7] Add a Controller to Handle the Callback URLs

### ==> edit ~/rails_apps/myapp/config/routes.rb and,

### ==> update the devise_for line to specify the name of the 
	 	controller that will be handling the callbacks


### ==> $APPROOT/config/Routes.rb should have the following:

Rails.application.routes.draw do
  devise_for :users, :controllers => { :omniauth_callbacks => "callbacks" } 		### ==> add this line
  resources :products
  root 'products#index'
end


### ==> Then, create a new file: 
	$APPROOT/app/controllers/callbacks_controller.rb

class CallbacksController < Devise::OmniauthCallbacksController
    def digitalocean
        @user = User.from_omniauth(request.env["omniauth.auth"])
        sign_in_and_redirect @user
    end
end



----- [8] Add Login/Logout links/buttons to the application.html.erb template
### ==> 
<% if user_signed_in? %>
  <li>
  <%= link_to('Logout', destroy_user_session_path, :method => :delete) %>        
  </li>
<% else %>
  <li>
  <%= link_to('Login', new_user_session_path)  %>  
  </li>
<% end %>