Question

I have seen this code in ShoppingCart class in Music Store MVC3 tutorial: http://www.asp.net/mvc/tutorials/mvc-music-store

// We're using HttpContextBase to allow access to cookies.
        public string GetCartId(HttpContextBase context)
        {
            if (context.Session[CartSessionKey] == null)
            {
                if (!string.IsNullOrWhiteSpace(context.User.Identity.Name))
                {
                    context.Session[CartSessionKey] =
                        context.User.Identity.Name;
                }
                else
                {
                    // Generate a new random GUID using System.Guid class
                    Guid tempCartId = Guid.NewGuid();
                    // Send tempCartId back to client as a cookie
                    context.Session[CartSessionKey] = tempCartId.ToString();
                }
            }
            return context.Session[CartSessionKey].ToString();
        }

Why is GUID needed? I am asking for somebody to explain what is it used for in this example.

Answer 1

Have a look at part 8 of that tutorial, under the heading “Managing the Shopping Cart business logic” – this explains the purpose of that code.

Basically, the GUID is used to uniquely identify a user, without forcing them to have logged in, so that the application can keep track of items that they have put into the shopping cart.