ASP.NET MVC3 + Entity Framework项目中,从控制器传递匿名对象到视图非常常见,原本以为用dynamic能轻松搞定,最后发现我错了:
Controller:
代码如下 |
复制代码 |
public ActionResult Index() { testContext context = new testContext(); dynamic data = context.People .Join(context.Pets, person => person.Id, Pet => Pet.Pid, (person, pet) => new { Person = person.Name, Pet = pet.Name }); return View(data); }
View:
@model dynamic
@foreach(var item in Model) { @(item.Person)<text>,</text>@(item.Pet)<br /> }
|
其原因是C#的编译器总是将匿名类型编译成internal的,当通过dynamic访问在当前上下文不可见的成员的时候,就会引发异常。问题重现:
代码如下 |
复制代码 |
using System; using System.Collections.Generic; using System.Linq;
namespace Controller { public class Test { /// <summary> /// 模拟匿名对象匿名类 /// </summary> private class Anonymous { public string Person { get; set; } public string Pet { get; set; } }
public dynamic GetValue() { return new Anonymous(); } } }
namespace View { using Controller;
class Program { static void Main(string[] args) { dynamic anonymous = new Test().GetValue(); Console.WriteLine(anonymous.Person);
Console.ReadKey(); } } }
|
以前都用老赵的ToDynamic方法解决,今天在.NET 4.0的System命名空间下看到一个类Tuple,了解后发现用它也可以解决上边的问题:
Controller:
代码如下 |
复制代码 |
public ActionResult Index() { testContext context = new testContext(); dynamic data = context.People .Join(context.Pets, person => person.Id, Pet => Pet.Pid, (person, pet) => new { Person = person.Name, Pet = pet.Name }) .ToList().Select(item => Tuple.Create(item.Person, item.Pet)); return View(data); }
View:
@model IEnumerable<Tuple<string, string>>
@foreach(var item in Model) { @(item.Item1)<text>,</text>@(item.Item2)<br /> }
|