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 :tasks, :through => :assignments      #assignment belongs_to :task belongs_to :user  #task has_many :assignments has_many :users, :through => :assignments 

I would like to get a task then navigation to its assigned users, and sort the user list alphabetically.

I keep thinking that I should be able to add the :order clause to has_many :users, :through => :assignments like this:

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

however this does not work.

How can I sort users by last_name when given a task?

Answer 1

Since condition arguments are deprecated in Rails 4, one should use scope blocks:

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