A Rails model example for generating slugs for a "slug" parameter/column

slug.rb

before_validation :slug_to_slug

  protected

  def slug_to_slug
    self.slug = self.to_slug
  end

  def to_slug(param=self.slug)
    # strip the string
    ret = param.strip

    #blow away apostrophes
    ret.gsub! /['`]/, ""

    # @ --> at, and & --> and
    ret.gsub! /\s*@\s*/, " at "
    ret.gsub! /\s*&\s*/, " and "

    # replace all non alphanumeric, periods with dash
    ret.gsub! /\s*[^A-Za-z0-9\.]\s*/, '-'

    # replace underscore with dash
    ret.gsub! /[-_]{2,}/, '-'

    # convert double underscores to single
    ret.gsub! /-+/, "-"

    # strip off leading/trailing dash
    ret.gsub! /\A[-\.]+|[-\.]+\z/, ""

    ret
  end