Streaming (CSV) data in Rails 3.2

foo_controller.rb

class FooController
  respond_to :csv

  def index
    @foos = Foo.scoped
    if stale?(:last_modified => Foo.something)
       respond_with @gta do |format|
         format.csv { stream_csv @foo }
       end
    end
  end

  def stream_csv(resource, options)
    stream_resource do |y|
      # csv headers
      y << resource.klass.to_csv_header
      # csv rows
      resource.find_each(options) { |item|
        y << item.to_csv
      }
    end
  end

  def stream_resource(&block)
    # theoretically this should make unicorn pass-through
    headers['X-Accel-Buffering'] = 'no'
    # OK, and generate stream
    self.status = 200
    self.response_body = Enumerator.new &block
  end

end