Rails 3: how to require at least one field not to be blank

I have a model that has several properties. I want to va开发者_StackOverflow中文版lidate that at least one of those properties is set. I saw the post here, but the errors.add_to_base is now deprecated in Rails 3 and was wondering what the new solution might be.

---

It's now simply

errors.add(:base, "message")