class Book
  include Mongoid::Document
  field :t, :as => :title
end

b = Book.new
b.t
# => NoMethodError: undefined method `t' for #<Book _id: 4f0b4d99ad8a54813e000002, _type: nil, t: nil>
b.title
# => nil
b.title = "Hey"
b.t
# => "Hey"
b.title_changed?
# => NoMethodError: undefined method `title_changed?' for #<Book _id: 4f0b4d99ad8a54813e000002, _type: nil, t: "Hey">
b.t_changed?
# => true

This seems confusing: I have make sure to use the aliased label name all the time, else I'm vulnerable to NoMethodErrors. However, when checking dirty fields, I have to use the original field names.

I think this should be that the original field name should always work, and it would be nice if <code>[alias]_changed?</code> also worked. Let me know if you'd like me to split these out into multiple issues, etc.

Jon