Revert overriding #to_param method defined in models for ActiveAdmin

active_admin.rb

ActiveAdmin.setup do |config|
  # ...
  config.before_filter :revert_friendly_id, :if => -> { !devise_controller? && resource_controller? }
end

# override #to_param method defined in model in order to make AA generate
# routes like /admin/page/:id/edit
ActiveAdmin::BaseController.class_eval do

  protected
  def resource_controller?
    self.class.superclass.name == "ActiveAdmin::ResourceController"
  end

  def revert_friendly_id
    model_name = self.class.name.match(/::(.*)Controller$/)[1].singularize
    # Will throw a NameError if the class does not exist
    Module.const_get model_name

    eval(model_name).class_eval do
      def to_param
        id.to_s
      end
    end
  rescue NameError
  end
end