omniauth strategy

app/controllers/application_controller.rb

@@ -1,3 +1,8 @@
 class ApplicationController < ActionController::Base
   protect_from_forgery with: :exception
+
+  def current_user
+    @current_user ||= User.find_by(id: session[:user_id])
+  end
+  helper_method :current_user
 end