to_slug method for ActiveRecord model

model.rb

# Hook this up in your ActiveRecord model for a nicer slug
# I use it on before_save :to_slug

def to_slug
  # Translate usual characters encountered
  convert_map = {
    /\@/ => ' at ',
    /\&/ => ' and ',
    /\%/ => ' percent ',
  }
  convert_map.each do |pattern, replacement|
    self.slug = slug.gsub(pattern, replacement)
  end
  
  self.slug = slug.downcase.strip.gsub(' ', '-').gsub(/[^\w-]/, '').gsub(/[-]{2,}/, '-').gsub(/^-/, '').gsub(/-$/, '')
end