Dynamic omniauth

omniauth_controller.rb

class OmniauthController < ApplicationController
  def start
    request_phase(:facebook, client_id, client_secret)
  end

  def callback
    callback_phase(:facebook, client_id, client_secret) do
      render :text => "Done!"
    end
  end

  def request_phase(name, *args, &block)
    strategy = ::OmniAuth::Strategies.const_get(::OmniAuth::Utils.camelize(name.to_s))
    block  ||= lambda { |env| [404, { "Content-Type" => "text/plain" }, []] }
    strategy.new(block, name, *args).call(env)
  end

  def callback_phase(name, *args, &block)
    strategy = ::OmniAuth::Strategies.const_get(::OmniAuth::Utils.camelize(name.to_s))
    strategy.new(block, name, *args).call(env)
  end
end