def update_urlname!
      new_urlname = nested_url_name(slug)
      if urlname != new_urlname
        legacy_urls.create(urlname: urlname)
        update_column(:urlname, new_urlname)
      end
    end
def update_urlname!
      new_urlname = nested_url_name(slug)
      if urlname != new_urlname
        legacy_urls.create(urlname: urlname)
        update_column(:urlname, new_urlname)
      end
    end
Makes a slug of all ancestors urlnames including mine and delimit them be slash.
 So the whole path is stored as urlname in the database.