C# ASP.NET HttpWebRequest automatically decodes ampersand (&) values from query string?

Assume the following Url:

"http://server/application1/TestFile.aspx?Library=Testing&Filename=Documents & Functions + Properties.docx&Save=true"

I use HttpUtility.UrlEncode() to encode the value of the Filename parameter and I create the following Url:

"http://server/application1/TestFile.aspx?Library=Testing&Filename=Documents%20%26%20Functions%20%2B%20Properties.docx&Save=true"

I send the following (encoded version) of request from a client to a C# Web Application. On the server when I process the request I have a problem. The HttpRequest variable contains the query string partially decoded. That is to say when I try to use or quick wa开发者_Python百科tch the following properties of HttpRequest they have the following values.

Property = Value
================
HttpRequest.QueryString = "{Library=Testing&Filename=Documents+&+Functions+++Properties.docx&Save=true}"

HttpRequest.Url = "{http://server/application1/TestFile.aspx?Library=Testing&Filename=Documents & Functions + Properties.docx&Save=true}"

HttpRequest.Url.AbsoluteUri = "http://server/application1/TestFile.aspx?Library=Testing&Filename=Documents%20&%20Functions%20+%20Properties.docx&Save=true"

I have also checked the following properties but all of them have the & value decoded. However all other values remain properly encoded (e.g. space is %20).

HttpRequest.Url.OriginalString

HttpRequest.Url.Query

HttpRequest.Url.PathAndQuery

HttpRequest.RawUrl

There is no way I can read the value of the parameter Filename properly. Am I missing something?

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The QueryString property returns a NameValueCollection object that maps the querystring keys to fully-decoded values.

You need to write Request.QueryString["FileName"].

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I'm answering this question many years later because I just had this problem and figured out the solution. The problem is that HttpRequest.Url isn't really the value that you gave. HttpRequest.Url is a Uri class and that value is the ToString() value of that class. ToString() for the Uri class decodes the Url. Instead, what you want to use is HttpRequest.Url.OriginalString. That is the encoded version of the URL that you are looking for. Hope this helps some future person having this problem.

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What happens when you don't use UrlEncode? You didn't show how exactly you are using the url that you created using UrlEncode, so it is quite possible that things are just being double encoded (lots of the framework will encode the URLs for you automatically).

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FWIW I ran into this same problem with RavenDB (version 960). They implement their own HttpRequest object that behaves just like this -- it first decodes just the ampersands (from %26 to &) and then decodes the entire value. I believe this is a bug.

A couple of workarounds to this problem:

1. Implement your own query string parsing on the server. It's not fun but it is effective.
2. Double-encode ampersands. First encode just the ampersands in the string, then encode the entire string. (It's an easy solution but not extensible because it puts the burden on the client.)