Helper method to add reorder rows functionality to active admin index table view.

Add gem to Gemfile:

gem activeadmin-mongoid-reorder

Add Monogoid::Reorder to the model declaration you want to be reordarable. This will add reorder_objects class method, _position field and set default sorting order to :_position => :desc - so haviest goes first.

Example:

class Page
  include Mongoid::Document
  include Mongoid::Reorder

  # Fields
  field :title,     :type => String
  field :content,   :type => String
end

To the end of admin registration method of each reordarable model add the following generic helper:

collection_action :reorder, :method => :put do
  render :text => resource_class.reorder_objects(params[:ids])
end

Reorder table type should be specified for index view, here is an example how this should look like:

index :as => :reorder_table do
  column :title
  default_actions
end

And finally enable sorting js functionality. jQuery-ui is included by activeadmin by default, so all you need is to include activeadmin_reoder_table in active_admin.js.coffee:

#= require activeadmin_reorder_table

That's it.