Is there a built-in method to validate that two fields in combination are unique?
e.g. if my table is :
I am interested in this too. Does anybody have any ideas?
validates_uniqueness_of :username, :scope => :password
http://api.rubyonrails.org/classes/ActiveRecord/Validations/ClassMethods.html#M000944
(this is an extra query. You could write a unique index and rescue the exception).