什么是最简单的方法code反对在C＃中的属性时，我有属性的字符串名字？例如，我想允许用户通过他们的选择（使用LINQ）的属性来订购一些搜索结果。他们会选择属性在用户界面中排序依据 - 当然字符串值。有没有一种方法可以直接使用该字符串作为LINQ查询的性能，而不必使用条件逻辑（的if / else，开关）的字符串映射到属性。反思？

What's the simplest way to code against a property in C# when I have the property name as a string? For example, I want to allow the user to order some search results by a property of their choice (using LINQ). They will choose the "order by" property in the UI - as a string value of course. Is there a way to use that string directly as a property of the linq query, without having to use conditional logic (if/else, switch) to map the strings to properties. Reflection?

从逻辑上讲，这就是我想要做的：

Logically, this is what I'd like to do:

query = query.OrderBy(x => x."ProductId");

更新： 我最初没有指定我使用LINQ到实体 - 看起来反射（至少使用getProperty，的GetValue方法）并没有转化为L2E

Update: I did not originally specify that I'm using Linq to Entities - it appears that reflection (at least the GetProperty, GetValue approach) does not translate to L2E.

推荐答案

我会提供这种替代其他人都已经发布。

I would offer this alternative to what everyone else has posted.

System.Reflection.PropertyInfo prop = typeof(YourType).GetProperty("PropertyName");

query = query.OrderBy(x => prop.GetValue(x, null));

这可以避免重复调用反射API获得的财产。现在唯一的重复调用获得的价值。

This avoids repeated calls to the reflection API for obtaining the property. Now the only repeated call is obtaining the value.

然而

我会主张使用的PropertyDescriptor 代替，因为这将允许自定义 TypeDescriptor s到分配给你的键入，从而可以有轻量的操作：获取属性和值。在没有定制的描述符，将回落到反射无论如何。

I would advocate using a PropertyDescriptor instead, as this will allow for custom TypeDescriptors to be assigned to your type, making it possible to have lightweight operations for retrieving properties and values. In the absence of a custom descriptor it will fall back to reflection anyhow.

PropertyDescriptor prop = TypeDescriptor.GetProperties(typeof(YourType)).Find("PropertyName");

query = query.OrderBy(x => prop.GetValue(x));

至于加速起来，看看马克碎石的HyperDescriptor项目于$ C $的CProject。我用这个大获成功;这是一个生命的救星为高性能数据绑定和动态性操作的业务对象。

As for speeding it up, check out Marc Gravel's HyperDescriptor project on CodeProject. I've used this with great success; it's a life saver for high-performance data binding and dynamic property operations on business objects.