Using the shop from the book i created a product_type model.
A product belongs_to product_typr and a product_type has_many product.
the best thing i managed to do is that :
controller :shop do get “shop” => “shop#index” end
in routes and :
<%= link_to product_type.name, shop_path(product_type) %>
for the link directing to shop
Please i really really need some help here, i am trying to do it since 4 days and i asked in a lot of forums without any solution.