public static void DeleteOnSubmit(this DbSet<Product> source, Product product)
 {
     source.Remove(product);
 }
 /// <summary>
 /// Initializes a new instance of the <see cref="ShoppingCartItem"/> class.
 /// </summary>
 /// <param name="product">The product.</param>
 public ShoppingCartItem(Product product)
 {
     Product = product;
 }
 public static void InsertOnSubmit(this DbSet<Product> source, Product product)
 {
     if (product.ProductID == default(int))
     {
         // New entity
         source.Add(product);
     }
     else
     {
         // Existing entity
         source.Attach(product);
     }
 }