public void AddItem(ChineseTeaShopEntities dbContext, TeaProduct product, decimal finalPrice, int quantity, string userId)
        {
            //Search whether cart has desired product
            ShRecord record = recordCollection.FirstOrDefault(m => m.TeaProduct == product);

            if (record == null || record.IsCompleted == true)
            {
                ShRecord updateRecord = new ShRecord {
                    ProductId = product.ID, TeaProduct = product, FinalPrice = finalPrice, Quantity = quantity, AddTime = DateTime.Now, UserId = userId
                };

                //update database
                dbContext.ShRecords.Add(updateRecord);
                dbContext.SaveChanges();

                //update shopping cart
                recordCollection.Add(updateRecord);
            }
            else if (record.IsCompleted == false)
            {
                record.Quantity              += quantity;
                record.FinalPrice            += finalPrice;
                dbContext.Entry(record).State = System.Data.Entity.EntityState.Modified;
                dbContext.SaveChanges();
            }
        }
 public void RemoveLine(TeaProduct product)
 {
     recordCollection.RemoveAll(m => m.TeaProduct.ID == product.ID);
 }