gistfile1.rb

  def filter_url_helper(filter_key, filter_value)
    product_group_query = params[:product_group_query] != nil ? Array.new(params[:product_group_query]) : nil
    
    if product_group_query == nil 
      return "/t/#{params[:id].join('/')}/s/#{filter_key}/#{filter_value}"
    end
    if product_group_query.index(filter_key) == nil
      return "/t/#{params[:id].join('/')}/s/#{product_group_query.join('/')}/#{filter_key}/#{filter_value}"
    else
      product_group_query[product_group_query.index(filter_key)+1] = filter_value      
      return "/t/#{params[:id].join('/')}/s/#{product_group_query.join('/')}"
    end

  end

#view code
<dl>
	<dt>Price Bands</dt>
	<dd><a href="<%=filter_url_helper('price_between', '0,50') %>">less than £50</a></dd>
	<dd><a href="<%=filter_url_helper('price_between', '50,100') %>">£50 - £100</a></dd>
	<dd><a href="<%=filter_url_helper('price_between', '100,500') %>">£100 - £500</a></dd>
</dl>

<dl>
	<dt>Brands</dt>
	<% @brands.each do |brand| -%>
		<% brand.root.children.each do |taxon| %>
			<dd><a href="<%=filter_url_helper('in_taxon', taxon.name) %>"><%= taxon.name %></a></dd>
		<% end -%>
	<% end -%>
</dl>