app/views/admin/products/_form.haml
= simple_form_for [:admin, product], :html => {:multipart => true} do |form|
= form.hidden_field :photo_cache
= form.input :name
= form.association :category
= form.input :price
= form.input :photo, :as => :file
%label (Current Photo)
= product.thumbnail if product.photo
= form.button :submit