rails3-jquery-autocomplete in ActiveAdmin

orders.rb

form do |f|
  f.form_buffers.last << f.autocompleted_input(:product_name, url: autocomplete_product_name_orders_path, label: 'Product')
end

orders_controller.rb

class OrdersController < ApplicationController
  autocomplete :product, :name, full: true
end

routes.rb

resources :orders do
  get :autocomplete_product_name, on: :collection
end