<% form_for @cart do |cart| %>
    <ul class='cart'>
        <% cart.fields_for :items do |i| %>
            <li class='cart-item'>
                <span class='quantity'><%= check_box_tag :remove %></span>
                <span class='quantity'><%= i.text_field :quantity, :size => 2 %>X</span>
                <span class='name'><%= item.product.name %></span>
            </li>
        <% end %>
    </ul>
    <%= submit_tag 'update' %>
<% end %>