Pretty URLs, Separation of Layers and O/R Mapping in Web Forms ASP.NET 2.0

using System;
using System.Collections.Generic;
using System.Collections.Specialized;  //needed for IOrderedDictionary
using System.Web;

using NHibernate.MapClasses;
using NHibernate;
using Routing.Module;
using NHibernate.Mapping;


/// <summary>
/// Summary description for BooksDB
/// </summary>
/// 
namespace MVC.Models
{
    public class BooksForSaleDB : IBooksForSale
    {

        public BooksForSaleDB()
        {
        }

        //-------------------cart manipulation methods-----------------------------------
        public List<CartMember> GetShoppingCart()
        {
            if (HttpContext.Current.Session["cart"] != null)
                return (List<CartMember>)HttpContext.Current.Session["cart"];
            else
                return null;
        }




        public void add_item_to_cart(int id)
        {
            CartMember CartEntry = new CartMember();
            Product SingleProduct = ShowByID(id);

            CartEntry.MemberId = id;
            CartEntry.TitleCart = SingleProduct.Title;
            CartEntry.UnitPrice = SingleProduct.Price;
            CartEntry.TotalUnitPrice = CartEntry.UnitPrice;
            CartEntry.Quantity = 1;


            if (HttpContext.Current.Session["cart"] != null)
            {
                int doublepos = FindDoubleEntry(id);
                if (doublepos == -1)
                    ((List<CartMember>)HttpContext.Current.Session["cart"]).Add(CartEntry);
                else
                {
                    CartEntry.TotalUnitPrice =
                        ((List<CartMember>)HttpContext.Current.Session["cart"])
                                             [doublepos].TotalUnitPrice + CartEntry.UnitPrice;
                    CartEntry.Quantity =
                        ((List<CartMember>)HttpContext.Current.Session["cart"])
                                           [doublepos].Quantity + 1;

                    ((List<CartMember>)HttpContext.Current.Session["cart"]).RemoveAt(doublepos);

                    ((List<CartMember>)HttpContext.Current.Session["cart"]).Add(CartEntry);



                }
            }
            else
            {
                List<CartMember> TempList = new List<CartMember>();
                TempList.Add(CartEntry);
                HttpContext.Current.Session.Add("cart", TempList);
            }
        }

        
        public void EmptyCart()
        {
            if (HttpContext.Current.Session["cart"] != null)
            {
                HttpContext.Current.Session["cart"] = null;

            }
        }

        //helper methods not in  the interface
        private int FindDoubleEntry(int WhatId)
        {
            int pos = -1;
            foreach (CartMember SingleEntry in (List<CartMember>)HttpContext.Current.Session["cart"])
            {
                pos++;
                if ((SingleEntry.MemberId == WhatId)) return pos;



            }
            return -1;

        }

        //-----------------------------------------------------------------------------
      
        public Product ShowByID(int id)
        {
            ISession session = RoutingClass.NHibernateCurrentSession;
            Product product;
            using (session.BeginTransaction())
            {
                product = session.Get<Product>(id);
                session.Transaction.Commit();
            }
            return product;
        }




        public IList<Product> ShowAllForSale()
        {
            ISession session = RoutingClass.NHibernateCurrentSession;
            IList<Product> ListOfProducts;
            using (session.BeginTransaction())
            {
                IQuery query = session.CreateQuery("from Product where Date_Available < getdate()");
                ListOfProducts = query.List<Product>();
                session.Transaction.Commit();
            }
            return ListOfProducts;
        }
        
        public int CreateOrder(IOrderedDictionary InputParameters,
                                                   ref List<CartMember> CartSession)
        {

            ISession session = RoutingClass.NHibernateCurrentSession;
            ITransaction transaction = session.BeginTransaction();


            Order order = new Order();

            order.Name = (string)InputParameters["Name"];
            order.Email = (string)InputParameters["Email"];
            order.Address = (string)InputParameters["Address"];
            order.Pay_Type = (string)InputParameters["Pay_Type"];


            foreach (CartMember SingleEntry in CartSession)
            {

                LineItem lineitem = new LineItem();

                lineitem.Product_Id = SingleEntry.MemberId; //order_id skipped
                lineitem.Quantity = SingleEntry.Quantity;
                lineitem.Unit_Price = SingleEntry.UnitPrice;

                order.AddLineItem(lineitem); //takes care of associations

            }


            try
            {
                session.Save(order);
                transaction.Commit();
                return 1;
            }
            catch (TransactionException) { return 0; }
        }
    }
}