module ActiveAdmin::Devise::Controller

def root_path
  namespace = ActiveAdmin.application.default_namespace.presence
  root_path_method = [namespace, :root_path].compact.join('_')
  path = if Helpers::Routes.respond_to? root_path_method
           Helpers::Routes.send root_path_method
         else
           # Guess a root_path when url_helpers not helpful
           "/#{namespace}"
         end
  # NOTE: `relative_url_root` is deprecated by Rails.
  #       Remove prefix here if it is removed completely.
  prefix = Rails.configuration.action_controller[:relative_url_root] || ''
  prefix + path
end