gistfile1.rb

  def sort_link(attribute, *args)
    attr_name = attribute.to_s
    name = (args.size > 0 && !args.first.is_a?(Hash)) ? args.shift.to_s : attr_name.humanize
    prev_attr, prev_order = params['q'].nil? ? '' '' : params['q']['s'].to_s.split(' ')

    options = args.first.is_a?(Hash) ? args.shift : {}
    current_order = prev_attr == attr_name ? prev_order : nil

    if options[:default_order] == :desc
      new_order = current_order == 'desc' ? 'asc' : 'desc'
    else
      new_order = current_order == 'asc' ? 'desc' : 'asc'
    end
    options.delete(:default_order)

    html_options = args.first.is_a?(Hash) ? args.shift : {}
    css = ['sort_link', current_order].compact.join(' ')
    html_options[:class] = [css, html_options[:class]].compact.join(' ')
    q = params['q'].nil? ? {} : params['q'].dup
    q.merge!(:s => "#{attr_name} #{new_order}")
    options.merge!(:q => q)
    link_to [ERB::Util.h(name), order_indicator_for(current_order)].compact.join(' ').html_safe,
            url_for(options),
            html_options
  end

  def order_indicator_for(order)
    if order == 'asc'
      '▲'
    elsif order == 'desc'
      '▼'
    else
      nil
    end
  end