如何在 C# 中为 URL 构建查询字符串? [英] How to build a query string for a URL in C#?

问题描述

从代码调用 Web 资源时的一项常见任务是构建查询字符串以包含所有必要的参数.虽然绝不是火箭科学，但您需要注意一些漂亮的细节，例如，如果不是第一个参数，则附加 &，对参数进行编码等.

A common task when calling web resources from a code is building a query string to including all the necessary parameters. While by all means no rocket science, there are some nifty details you need to take care of like, appending an & if not the first parameter, encoding the parameters etc.

实现它的代码很简单，但有点乏味:

The code to do it is very simple, but a bit tedious:

StringBuilder SB = new StringBuilder();
if (NeedsToAddParameter A) 
{ 
  SB.Append("A="); SB.Append(HttpUtility.UrlEncode("TheValueOfA")); 
}

if (NeedsToAddParameter B) 
{
  if (SB.Length>0) SB.Append("&"); 
  SB.Append("B="); SB.Append(HttpUtility.UrlEncode("TheValueOfB")); }
}

这是一项非常常见的任务，人们希望存在一个实用程序类，使其更加优雅和可读.扫描MSDN，没找到—这让我想到了以下问题:

This is such a common task one would expect a utility class to exist that makes it more elegant and readable. Scanning MSDN, I failed to find one—which brings me to the following question:

你所知道的最优雅的清洁方式是什么?

What is the most elegant clean way you know of doing the above?

推荐答案

如果您深入了解 QueryString 属性是一个 NameValueCollection.当我做了类似的事情时，我通常对序列化和反序列化感兴趣，所以我的建议是建立一个 NameValueCollection 然后传递给:

If you look under the hood the QueryString property is a NameValueCollection. When I've done similar things I've usually been interested in serialising AND deserialising so my suggestion is to build a NameValueCollection up and then pass to:

using System.Linq;
using System.Web;
using System.Collections.Specialized;

private string ToQueryString(NameValueCollection nvc)
{
    var array = (
        from key in nvc.AllKeys
        from value in nvc.GetValues(key)
            select string.Format(
                "{0}={1}",
                HttpUtility.UrlEncode(key),
                HttpUtility.UrlEncode(value))
        ).ToArray();
    return "?" + string.Join("&", array);
}

我想在 LINQ 中也有一种超级优雅的方法可以做到这一点......

I imagine there's a super elegant way to do this in LINQ too...

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