Takes the slug, downcases it and replaces non-word characters with a -

slug_convert.rb

  # Takes the slug, downcases it and replaces non-word characters with a -.
  # Feel free to override this method if you'd like different slug formatting.
  def normalize_slug_url
    return if self.name.blank?
    s = ActiveSupport::Multibyte.proxy_class.new(self.name).normalize(:kc)
    s.downcase!
    s.strip!
    s.gsub!(/[^a-z0-9\s-]/, '') # Remove non-word characters
    s.gsub!(/\s+/, '-') # Convert whitespaces to dashes
    s.gsub!(/-\z/, '') # Remove trailing dashes
    s.gsub!(/-+/, '-') # get rid of double-dashes
    self.url = s.to_s
  end