extend friendly_id to have more than 1 friendly_id for each model

friendly_id_ext.rb

module FriendlyId
  module ActiveRecordAdapter

    def has_another_friendly_id method, options={}
      if FriendlyId::on_ar3?
        class_attribute :friendly_ids if !self.respond_to?(:friendly_ids)
        self.friendly_ids ||= []
        config = Configuration.new(self, method, options)
        self.friendly_ids << config
      end
    end

  end
end


module FriendlyId
  module ActiveRecordAdapter
    module SluggedModel

    alias_method :orig_build_a_slug, :build_a_slug
    def build_a_slug
        friendly_ids.each do |config|
          text = generate_slug_text_for(config).to_s
          self.send("#{config.cache_column}=".to_sym, text)
        end
        orig_build_a_slug
      end

      def generate_slug_text_for config
        base = self.send(config.method).to_s
        if !base.nil? && !config.allow_nil?
          text = SlugString.new(base).normalize_for!(config).to_s
          SlugString.new(text).validate_for!(config)
        end
      end

    end
  end
end


module FriendlyId
  class TaskRunner

    def make_slugs
      validate_uses_slugs
      options = {
        :include => :slug,
        :limit   => (ENV["LIMIT"] || 100).to_i,
        :offset  => 0,
        :order   => ENV["ORDER"] || "#{klass.table_name}.id ASC",
      }.merge(task_options || {})

      while records = find(:all, options) do
        break if records.size == 0
        records.each do |record|
          record.save(:validate => false) unless record.slug?
          yield(record) if block_given?
        end
        options[:offset] += options[:limit]
      end
    end

  end
end