使用 C# 匿名类型 [英] Working with C# Anonymous Types

问题描述

我正在调用一个方法，该方法返回一个包含 c# 匿名类型对象的 List 变量.例如:

I am calling a method that returns a List variable that contains a c# Anonymous Type objects. For example:

List<object> list = new List<object>();
foreach ( Contact c in allContacts ) {
    list.Add( new {
        ContactID = c.ContactID,
        FullName = c.FullName
    });
}
return list;

如何在我正在处理的代码中引用这种类型的属性，例如

How do I reference this type properties in the code I am working on like for example

foreach ( object o in list ) {
    Console.WriteLine( o.ContactID );
}

我知道我的样本是不可能的，我这样写只是为了说明我需要准确识别匿名类型的每个属性.

I know that my sample is not possible, I have only wrote that way to say that I need to identify each property of the anonymous type exactly.

谢谢！

解决方案:

不仅仅是一个答案是正确的和/或提出了一个可行的解决方案.我最终使用了 Greg 答案的选项 3.我学到了一些关于 .NET 4.0 中的 dynamic 非常有趣的东西！

Not just one of the answer is correct and/or suggest a working solution. I have ended up to using Option 3 of Greg answer. And I learned something very interesting regarding the dynamic in .NET 4.0!

推荐答案

你不能返回一个匿名类型的列表，它必须是一个 object 的列表.因此，您将丢失类型信息.

You can't return a list of an anonymous type, it will have to be a list of object. Thus you will lose the type information.

选项 1
不要使用匿名类型.如果您尝试在多个方法中使用匿名类型，请创建一个真正的类.

Option 1
Don't use an anonymous type. If you are trying to use an anonymous type in more than one method, then create a real class.

选项 2
不要将您的匿名类型向下转换为 object.(必须是一种方法)

var list = allContacts
             .Select(c => new { c.ContactID, c.FullName })
             .ToList();

foreach (var o in list) {
    Console.WriteLine(o.ContactID);
}

选项 3
使用动态关键字.(需要 .NET 4)

Option 3
Use the dynamic keyword. (.NET 4 required)

foreach (dynamic o in list) {
    Console.WriteLine(o.ContactID);
}

选项 4
使用一些肮脏的反射.

Option 4
Use some dirty reflection.

这篇关于使用 C# 匿名类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！