#Clearance Clearance is a simple Ruby on Rails authentication with email & password.

#OmniAuth Facebook OmniAuth Facebook is Facebook OAuth2 Strategy for OmniAuth

#Integrate OmniAuth Facebook with Clearance

To setup clearance, visit https://github.com/estelleccl/how_to_use_clearance or https://github.com/thoughtbot/clearance

1. add gem 'omniauth' into Gemfile

2. add gem 'omniauth-facebook' into Gemfile

3. run bundle in the terminal

4. create omniauth.rb file in config\initializers and paste the following code into the file:

   	Rails.application.config.middleware.use OmniAuth::Builder do
    	  provider :facebook, 'APP_KEY', 'APP_SECRET'
   	end
   

   *replace 'APP_KEY' and 'APP_SECRET' with your own keys which you get in facebook

5. create authentication.rb file in app\models and paste the following code into the file:

   	class Authentication < ActiveRecord::Base
   
    	 belongs_to :user
   
   	  def self.create_with_omniauth(auth_hash)
   	    create! do |auth|
   	      auth.provider = auth_hash["provider"]
   	      auth.uid = auth_hash["uid"]
   	      auth.token = auth_hash["credentials"]["token"]
   	    end
   	  end
   
   	  def update_token(auth_hash)
   	    self.token = auth_hash["credentials"]["token"]
   	    self.save
   	  end
   
   	end
   

6. Go to config\routes.rb and add the following code into the file:

   	get "/auth/:provider/callback" => "sessions#create_from_omniauth"
   

7. create sessions_controller.rb file in app\controllers and paste the following code into the file:

   	class SessionsController < Clearance::SessionsController
   
   	  def create_from_omniauth
   	    auth_hash = request.env["omniauth.auth"]
   
   	    authentication = Authentication.find_by_provider_and_uid(auth_hash["provider"], auth_hash["uid"]) || Authentication.create_with_omniauth(auth_hash)
   	    if authentication.user
   	      user = authentication.user 
   	      authentication.update_token(auth_hash)
   	      @next = root_url
   	      @notice = "Signed in!"
   	    else
   	      user = User.create_with_auth_and_hash(authentication,auth_hash)
   	      @next = edit_user_path(user)   
   	      @notice = "User created - confirm or edit details..."
   	    end
   	    sign_in(user)
   	    redirect_to @next, :notice => @notice
   	  end
   	end
   
   

8. Go to app/models/users and add the following code into the file:

   	has_many :authentications, :dependent => :destroy
     
     def self.create_with_auth_and_hash(authentication,auth_hash)
       create! do |u|
         u.first_name = auth_hash["info"]["first_name"]
         u.email = auth_hash["extra"]["raw_info"]["email"]
         u.authentications<<(authentication)
       end
     end
   
     def fb_token
       x = self.authentications.where(:provider => :facebook).first
       return x.token unless x.nil?
     end
     
     def password_optional?
       true
     end
   
   

9. run rails g migration create_authentications uid token provider user_id in the terminal

10. go to db/migrate and find <timestamps_create_authentications.rb and add the following code into the file:

    	t.timestamps null: false
    

11. run bundle exec rake db:migrate in the terminal

    	make sure authentications table with uid, token, provider columns has been created
    

12. append the following code in ``` config/routes.rb````

    	resources :users, only: [:show, :edit, :update, :destroy] 
    

    *make sure there is no duplicates in the routes
    

#References

1. https://github.com/thoughtbot/clearance
2. https://github.com/estelleccl/how_to_use_clearance
3. https://gist.github.com/stevebourne/2394427

#Errors and solutions

1. https://github.com/estelleccl/how_to_integrate_clearance_wtih_facebook/blob/master/errors_and_solutions.md