Admin Order guest checkout status

app/controllers/spree/admin/orders/customer_details_controller_decorator.rb

@@ -1,7 +1,20 @@
 Spree::Admin::Orders::CustomerDetailsController.class_eval do
+  before_filter :set_guest_checkout_status, only: :update
+
   # Inherit CanCan permissions for the current order
   def model_class
     load_order unless @order
     @order
   end
+
+  private
+
+  def set_guest_checkout_status
+    registered_user = Spree::User.find_by_email(params[:order][:email])
+
+    params[:order][:guest_checkout] = registered_user.nil?
+
+    return unless registered_user
+    @order.user_id = registered_user.id
+  end
 end