long polling，因为我们是Web 2.0的世道，所以什么刷新呀越少越好，自然地、无缝的交互不断被提倡，方式就是使用Ajax来更新，但是，这里就有问题了，局部更新你需要不断http请求，少了还可以，但是多了呢？Phil举个例子，在他们将近1百万的用户中，如果有10万人在线呢？你的服务器需要接受到10万个请求，并且如果一个页面中请求的连接多、请求频繁，服务器负载就不简单控制了。所以，Phil说“使用long polling呀”，恩呢，这就是我一直想要寻求的技术（嘿嘿，我是技术新手，不懂怎么描述它）~设置在50秒内等待请求，极大地减缓了服务器压力，不过你也是最多把它减少10万*n多点，所以，如果你的服务器端软件不行那就嗝屁了
先说下背景，有这样几个类：Princess, Unicorn, Castle, and LadyInWaiting。其中Princess能够拥有很多Unicorn、Castle以及Ladyinwaiting,但是一个Castle中只能有一个Ladyinwaiting。每一个Castle都是按照位置来做标记，他具有一个符合类型ImaginaryWorld。
完整的Model代码：
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Data;
using System.Data.Entity;
using System.Data.Entity.Database;
using System.Data.Entity.Infrastructure;
using System.Data.Metadata.Edm;
using System.Data.Objects;
using System.Linq;
namespace Magic.Unicorn
{
public class Princess : IPerson
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection Unicorns { get; set; }
public virtual ICollection LadiesInWaiting { get; set; }
}
public class Unicorn
{
public int Id { get; set; }
public string Name { get; set; }
[Timestamp]
public byte[] Version { get; set; }
public int PrincessId { get; set; } // FK for Princess reference
public virtual Princess Princess { get; set; }
}
public class Castle
{
[Key]
public string Name { get; set; }
public Location Location { get; set; }
public virtual ICollection LadiesInWaiting { get; set; }
}
[ComplexType]
public class Location
{
public string City { get; set; }
public string Kingdom { get; set; }
public ImaginaryWorld ImaginaryWorld { get; set; }
}
[ComplexType]
public class ImaginaryWorld
{
public string Name { get; set; }
public string Creator { get; set; }
}
public class LadyInWaiting : IPerson
{
[Key, Column(Order = 0)]
[DatabaseGenerated(DatabaseGenerationOption.None)]
public int PrincessId { get; set; } // FK for Princess reference
[Key, Column(Order = 1)]
public string CastleName { get; set; } // FK for Castle reference
public string FirstName { get; set; }
public string Title { get; set; }
[NotMapped]
public string Name
{
get
{
return String.Format("{0} {1}", Title, FirstName);
}
}
public virtual Castle Castle { get; set; }
public virtual Princess Princess { get; set; }
}
public interface IPerson
{
string Name { get; }
}
public class UnicornsContext : DbContext
{
public DbSet Unicorns { get; set; }
public DbSet
Princesses { get; set; }
public DbSet LadiesInWaiting { get; set; }
public DbSet Castles { get; set; }
}
public class UnicornsContextInitializer
: DropCreateDatabaseAlways
{
protected override void Seed(UnicornsContext context)
{
var cinderella = new Princess { Name = "Cinderella" };
var sleepingBeauty = new Princess { Name = "Sleeping Beauty" };
var snowWhite = new Princess { Name = "Snow White" };
new List
{
new Unicorn { Name = "Binky" , Princess = cinderella },
new Unicorn { Name = "Silly" , Princess = cinderella },
new Unicorn { Name = "Beepy" , Princess = sleepingBeauty },
new Unicorn { Name = "Creepy" , Princess = snowWhite }
}.ForEach(u => context.Unicorns.Add(u));
var efCastle = new Castle
{
Name = "The EF Castle",
Location = new Location
{
City = "Redmond",
Kingdom = "Rainier",
ImaginaryWorld = new ImaginaryWorld
{
Name = "Magic Unicorn World",
Creator = "ADO.NET"
}
},
};
new List
{
new LadyInWaiting { Princess = cinderella,
Castle = efCastle,
FirstName = "Lettice",
Title = "Countess" },
new LadyInWaiting { Princess = sleepingBeauty,
Castle = efCastle,
FirstName = "Ulrika",
Title = "Lady" },
new LadyInWaiting { Princess = snowWhite,
Castle = efCastle,
FirstName = "Yolande",
Title = "Duchess" }
}.ForEach(l => context.LadiesInWaiting.Add(l));
}
}
public class Program
{
public static void Main(string[] args)
{
DbDatabase.SetInitializer(new UnicornsContextInitializer());
// Many of the code fragments can be run by inserting them here
}
}
}
private void MigrateShoppingCart(string UserName)
{
// Associate shopping cart items with logged-in user
var cart = ShoppingCart.GetCart(this.HttpContext);
cart.MigrateCart(UserName);
Session[ShoppingCart.CartSessionKey] = UserName;
}
下面是登录函数：
[HttpPost]
public ActionResult LogOn(LogOnModel model, string returnUrl)
{
if (ModelState.IsValid)
{
if (MembershipService.ValidateUser(model.UserName, model.Password))
{
MigrateShoppingCart(model.UserName);
FormsService.SignIn(model.UserName, model.RememberMe);
if (Url.IsLocalUrl(returnUrl))
{
return Redirect(returnUrl);
}
else
{
return RedirectToAction("Index", "Home");
}
}
else
{
ModelState.AddModelError("", "The user name or
password provided is incorrect.");
}
}
// If we got this far, something failed, redisplay form
return View(model);
}
以及注册函数：
[HttpPost]
public ActionResult Register(RegisterModel model)
{
if (ModelState.IsValid)
{
// Attempt to register the user
MembershipCreateStatus createStatus =
MembershipService.CreateUser(model.UserName, model.Password, model.Email);
if (createStatus == MembershipCreateStatus.Success)
{
MigrateShoppingCart(model.UserName);
FormsService.SignIn(model.UserName, false /* createPersistentCookie
*/);
return RedirectToAction("Index", "Home");
}
else
{
ModelState.AddModelError("", AccountValidation.ErrorCodeToString(createStatus));
}
}
// If we got this far, something failed, redisplay form
ViewBag.PasswordLength = MembershipService.MinPasswordLength;
return View(model);
}
紧接着的付款需要使用付款控制器，首先自然是创建一个啦：
using System;
using System.Linq;
using System.Web.Mvc;
using MvcMusicStore.Models;
namespace MvcMusicStore.Controllers
{
[Authorize]
public class CheckoutController : Controller
{
MusicStoreEntities storeDB = new MusicStoreEntities();
const string PromoCode = "FREE";
因为我们其实不是要实现真的付款过程，所以使用一个促销码来代替。
//
// GET: /Checkout/AddressAndPayment
public ActionResult AddressAndPayment()
{
return View();
}
//
// POST: /Checkout/AddressAndPayment
[HttpPost]
public ActionResult AddressAndPayment(FormCollection values)
{
var order = new Order();
TryUpdateModel(order);
try
{
if (string.Equals(values["PromoCode"], PromoCode,
StringComparison.OrdinalIgnoreCase) == false)
{
return View(order);
}
else
{
order.Username = User.Identity.Name;
order.OrderDate = DateTime.Now;
//Save Order
storeDB.AddToOrders(order);
storeDB.SaveChanges();
//Process the order
var cart = ShoppingCart.GetCart(this.HttpContext);
cart.CreateOrder(order);
return RedirectToAction("Complete",
new { id = order.OrderId });
}
}
catch
{
//Invalid - redisplay with errors
return View(order);
}
}
当完成以后，我们就给个提示：
//
// GET: /Checkout/Complete
public ActionResult Complete(int id)
{
// Validate customer owns this order
bool isValid = storeDB.Orders.Any(
o => o.OrderId == id &&
o.Username == User.Identity.Name);
if (isValid)
{
return View(id);
}
else
{
return View("Error");
}
}
最后就是添加视图，这个很简单，大家都会，不过因为需要验证，所以，我们复习下验证的特性：
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;
namespace MvcMusicStore.Models
{
[Bind(Exclude = "OrderId")]
public partial class Order
{
[ScaffoldColumn(false)]
public int OrderId { get; set; }
[ScaffoldColumn(false)]
public System.DateTime OrderDate { get; set; }
[ScaffoldColumn(false)]
public string Username { get; set; }
[Required(ErrorMessage = "First Name is required")]
[DisplayName("First Name")]
[StringLength(160)]
public string FirstName { get; set; }
[Required(ErrorMessage = "Last Name is required")]
[DisplayName("Last Name")]
[StringLength(160)]
public string LastName { get; set; }
[Required(ErrorMessage = "Address is required")]
[StringLength(70)]
public string Address { get; set; }
[Required(ErrorMessage = "City is required")]
[StringLength(40)]
public string City { get; set; }
[Required(ErrorMessage = "State is required")]
[StringLength(40)]
public string State { get; set; }
[Required(ErrorMessage = "Postal Code is required")]
[DisplayName("Postal Code")]
[StringLength(10)]
public string PostalCode { get; set; }
[Required(ErrorMessage = "Country is required")]
[StringLength(40)]
public string Country { get; set; }
[Required(ErrorMessage = "Phone is required")]
[StringLength(24)]
public string Phone { get; set; }
[Required(ErrorMessage = "Email Address is required")]
[DisplayName("Email Address")]
[RegularExpression(@"[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}",
ErrorMessage = "Email is is not valid.")]
[DataType(DataType.EmailAddress)]
public string Email { get; set; }
[ScaffoldColumn(false)]
public decimal Total { get; set; }
public List OrderDetails { get; set; }
}
}
最后就是更新一下错误提示页面：
@{
ViewBag.Title = "Error";
}
Error
We're sorry, we've hit an unexpected error.
Click here
if you'd like to go back and try that again.
现在我们的音乐商店基本上已经完工了，最后还一步骤就是添加导航。
接下来，添加信息提示的局部页面：
//
// GET: /ShoppingCart/CartSummary
[ChildActionOnly]
public ActionResult CartSummary()
{
var cart = ShoppingCart.GetCart(this.HttpContext);
ViewData["CartCount"] = cart.GetCount();
return PartialView("CartSummary");
}
注意到这个ChildActionOnly没？他是必须的，这样页面才知道这一款相当于一个局部的模板。
修改前台：
@Html.ActionLink("Cart
(" + ViewData["CartCount"] + ")",
"Index",
"ShoppingCart",
new { id = "cart-status" })
public virtual Genre Genre { get; set;
}
public virtual Artist Artist { get; set; }
public virtual List
OrderDetails { get; set; }
}
}
然后对于HomeController做出如下的修改：
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using MvcMusicStore.Models;
namespace MvcMusicStore.Controllers
{
public class HomeController : Controller
{
//
// GET: /Home/
MusicStoreEntities storeDB = new MusicStoreEntities();
public ActionResult Index()
{
// Get most popular albums
var albums = GetTopSellingAlbums(5);
return View(albums);
}
private List GetTopSellingAlbums(int count)
{
// Group the order details by album and return
// the albums with the highest count
return storeDB.Albums
.OrderByDescending(a => a.OrderDetails.Count())
.Take(count)
.ToList();
}
}
}
最后就是更新视图：让他能够正确显示这些专辑
@model List
@{
ViewBag.Title = "ASP.NET MVC Music Store";
}
