Polymorphic association with validation [Is it even possible ??]

I was wondering if I can have a polymorphic association and also a presence validation Let's say I have a `business` model and an `address` model, and `address` is polymorphic ``` class Business< ActiveRecord::Base has_one :address, as: :addressable validates_presence_of :address end class Address< ActiveRecord::Base belongs_to :addressable, polymorphic: true end ``` Is it possible to have the validation `validates_presence_of :address`? I am having issues when creating objects with this setup. Let's say first I create a business object like this ``` b = Business.new(name: "Hello23") b.address = Address.new(street: "House 43 BCD") b.save! ``` This doesn't work. It gives an `undefined method constantize for 0:Fixnum` and it makes sense to give an error, because when it tries to save the address to db it does not find an id of the addressable, since the business isn't yet saved and doesn't have an assigned id to it. But it isn't possible from the other side around either - I can't save the business without having an address. What is the best way to handle this kind of a situation? ****Apart from this what if I also want to have a validation on the address side like this** ``` validates_presence_of :addressable ``` I have been struggling with all this for about 2 days now. Let's see what ideas you people have ?**