Update using dirty

Babies_controller.rb

  def update
    if @baby.update_attributes(params[:baby])
      if baby.notify.changed?
        flash[:notice] = "Done"
      else
        redirect_to(root_url(:host => with_subdomain(@baby.subdomain)), :notice => 'Your baby was successfully updated and everyone has been told the good news.')
      end
    else
      render :action => "edit" 
    end
  end