this code: =form_fo :store_products do |f| = f.check_box :track_inventory
creates this html:
<input name="product_group[products_attributes][0][store_products_attributes}[1342647745501][track_inventory]" type="hidden" value="0">
<input id="product_group_products_attributes_0_store_products_attributes_1342647745501_track_inventory" name="product_group[products_attributes][0][store_products_attributes][1342647745501][track_inventory]" type="checkbox" value="1">
What is the reason for the first hidden element?