How do I include Responder in ActionController::Metal in Rails 3?

Question

I'm working a Rails 3 controller that has a very specific, limited purpose, and all I need is for it to respond_to :json.

This screencast says my controller can inherit from ActionController::Metal, and then just include the functionality I need to make things faster: http://rubyonrails.org/screencasts/rails3/action-controller

When my controller looks like this:

class FoldersController < ActionController::Metal
  respond_to :json
  def all
    respond_with Folder.all
  end
end

I get the error:

undefined method `respond_to' for FoldersController:Class

I've tried including Responder, ActionController::Responder, ActionController::Metal::Responder, but none of them work. What do I include to get this responder functionality?

Answer 1

ActionController::MimeResponds looks to be the path.