Rails 3: Validate combined values

Question

In Rails 2.x you can use validations to make sure you have a unique combined value like this:

validates_uniqueness_of :husband, :scope => :wife

Answer 1

Bear with me. The way the validates method in ActiveModel works is to look for a Validator.

:presence => true looks for PresenceValidator and passes the options: true to the validator's initializer.

I think you want

validates :husband, :presence => true, :uniqueness => {:scope => :wife}

(The uniqueness validator is actually part of ActiveRecord, not ActiveModel. It's really interesting how the developers set this up. It's quite elegant.)