Using form models (aka decorators) with Devise

To use a form model with devise, you can simply override #resource_class in a controller. A typical use case would be the registrations controller, as users will need some fields only on sign-up. Example:

class Frontend::Authentication::RegistrationsController < Devise::RegistrationsController

  private

  def resource_class
    FrontendUser::AsSignUp # my decorator class, extending from FrontendUser
  end

end