<% semantic_form_for(@product, :html => {:multipart => true}) do |f| %>
    <% f.inputs do %>
        <%= f.input :name %>
        <%= f.input :price %>
        <%= f.input :pno %>
        <%= f.input :description %>
        <%= f.input :shop_category %>
    <% end %>
<% end %>
Product belongs to Shop_category, Shop_category belongs to Shop.
How to change the line :
<%= f.input :shop_category %>
To show only shop_categories that belongs to Shop with id for example 15 instead of showing all shop_categories in the select box ?