class Page < ActiveRecord::Base
  acts_as_list
end

gem 'activeadmin-sortable'

ActiveAdmin.register Page do
  config.sort_order = 'position_asc' # assumes you are using 'position' for your acts_as_list column
  config.paginate   = false # optional; drag-and-drop across pages is not supported

  sortable # creates the controller action which handles the sorting

  index do
    sortable_handle_column # inserts a drag handle
    # other columns...
  end
end