gistfile1.rb

class User < ActiveRecord::Base
  def self.create_from_omniauth_data(data)
    user = new
    user.external_provider = true
    user.name = data['info']['email']
    user.email = data['info']['email']
    user.authorizations.build(:provider => omniauth['provider'], :uid => omniauth['uid'])
    user.save!
  end
  
  def self.find_or_create_by_omniauth(omniauth)
    provider = omniauth.fetch('provider')
    uid = omniauth.fetch('uid')
    
    if authorization = Authorization.find_by_provider_and_uid(provider, uid)
      self.find(authorization.user_id)
    else
      self.create_from_omniauth_data(omniauth)
    end
  end
end

def authenticate_and_redirect(user)
  session[:user_id] = user.id
  redirect_to root_url, alert: "Successfully logged in."
end


def create_by_provider
  # It's the Omniauth callback, Twitter and Facebook sends you here after authorization.
  omniauth = request.env["omniauth.auth"]
  if not omniauth
    redirect_to oops_url, alert: "We've found strange errors dealing with your external authentication, sorry."
    return
  end
  
  @user = User.find_or_create_by_omniauth(omniauth)
  authenticate_and_redirect(@user)
end