Omniauth and Devise Solution to get Facebook, Twitter and Google login authentication.

app.controllers.omniauth_callbacks_controller.rb

class OmniauthCallbacksController < Devise::OmniauthCallbacksController
  
  def twitter
    
    @player = Player.from_omniauth(request.env["omniauth.auth"])
    
    if @player.persisted?
      sign_in_and_redirect @player
      set_flash_message(:notice, :success, :kind => twitter) if is_navigational_format?
    else
      redirect_to new_player_registration_url
    end
  end
  
  
  def google
    
    @player = Player.from_omniauth(request.env["omniauth.auth"])
    
    if @player.persisted?
      sign_in_and_redirect @player
      set_flash_message(:notice, :success, :kind => "Google") if is_navigational_format?
    else
      
      redirect_to new_player_registration_url
    end
  end
  
  def facebook
    
    @player = Player.from_omniauth(request.env["omniauth.auth"])
    
    if @player.persisted?
      sign_in_and_redirect @player, :event => :authentication
      set_flash_message(:notice, :success, :kind => "Facebook") if is_navigational_format?
    else
      
      redirect_to new_player_registration_url
    end
  end
  
  def failure
    redirect_to root_path
  end
  
end

app.model.player.rb

class Player < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
  :recoverable, :rememberable, :trackable, :validatable, :omniauthable, :omniauth_providers => [:facebook,:twitter, :google]
  
  def self.from_omniauth(auth)
    where(provider: auth.provider, uid: auth.uid).first_or_create do |player|
      player.provider = auth.provider
      player.uid = auth.uid
      if player.provider == "twitter"
        player.email = "#{auth.info.nickname}@twitter.com"
      else
        player.email = auth.info.email
      end
      player.password = Devise.friendly_token[0,20]
    end
  end
end

config.routes.rb

Rails.application.routes.draw do
devise_for :players, :controllers => { :omniauth_callbacks => "omniauth_callbacks" }
end

devise.rb

Devise.setup do |config|
#...
config.omniauth :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET']
config.omniauth :twitter, ENV['TWITTER_KEY'], ENV['TWITTER_SECRET']
config.omniauth :google_oauth2, ENV['GOOGLE_KEY'], ENV['GOOGLE_SECRET'], name: 'google'
#...
end

Gemfile

#...
gem 'devise'
gem 'omniauth-twitter'
gem 'omniauth-facebook'
gem "omniauth-google-oauth2"
gem "figaro"
#...