if (shoppingCart != null)
{
String invID = req.getParameter("itemID");
// Gets detached instance
Inventory inv = catalog.getItemInventory(invID);
ShoppingCartItem si = new ShoppingCartItem(inv);
si.setQuantity(Integer.parseInt(req.getParameter("qty").trim()));
shoppingCart.addItem(si);
session.setAttribute(Util.ATTR_CART, shoppingCart);
session.setAttribute(Util.ATTR_CART_CONTENTS, shoppingCart.getCartContents());