My shopify auth

application_controller.rb

class ApplicationController < ActionController::Base
  protect_from_forgery
  force_ssl
  helper_method :current_shop, :shopify_session

protected

  def current_shop
    @current_shop ||= Shop.find(session[:shop_id]) if session[:shop_id].present?
  end
  
  def shopify_session
    if current_shop.nil?
      redirect_to new_login_url
    else
      begin
        session = ShopifyAPI::Session.new(current_shop.url, current_shop.token)
        ShopifyAPI::Base.activate_session(session)
        yield
      ensure
        ShopifyAPI::Base.clear_session
      end
    end
  end
end

login_controller.rb

def create
  omniauth = request.env['omniauth.auth']
  if omniauth && omniauth[:provider] && omniauth[:provider] == "shopify"
    shop = Shop.find_or_create_by_url(params[:shop].gsub(/https?\:\/\//, ""))
    shop.update_attribute(:token, omniauth['credentials'].token)
    shopify_session = ShopifyAPI::Session.new(shop.url, shop.token)
    session[:shop_id] = shop.to_param
    redirect_to root_url
  else
    flash[:error] = "Something went wrong"
    redirect_to root_url
  end
end

omnaiuth.rb

# goes in config/initializers/

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :shopify, Settings.api_key, Settings.api_secret,
    scope: 'write_products,write_script_tags,read_orders',
    setup: lambda { |env| params = Rack::Utils.parse_query(env['QUERY_STRING'])
                        env['omniauth.strategy'].options[:client_options][:site] = "http://#{params['shop']}" }
end

routes.rb

# then this to support the above controller in my routes

match '/auth/shopify/callback', :to => 'login#create'