How do I order a has_many through association in Ruby on Rails?

Question

Given the following AR models, I would like to sort users alphabetically by last name when given a handle to a task:

#user
has_many :assignments
has_many :ta         


        

Answer 1

Rails 3.x version:

has_many :users, :through => :assignments, :order => 'users.last_name, users.first_name'

UPDATE: This only works in Rails 3.x (maybe before that too). For 4+, see other answers.