c# - does Request.Querystring automatically url decode a string?

Question

I'm working with a page where I have a url like:
/directory/company/manufacturer

Using some re-write rules this gets re-written

testing with /directory/company/dunkin%26donuts/

Some manufacturers have an ampersand in their name. So I thought I could just replace the ampersand with %26. However, when I debug the code and hover over Request.QueryString it shows me {qq=company&manf=dunkin&donuts&cond=} and Request.QueryString["manf"] gives me 'dunkin'

If I use %24 ($) instead of ampersand, hovering over Request.QueryString gives me {qs=company&manf=dunkin%24donuts&cond=} and Request.QueryString["manf"] gives me 'dunkin$donuts'

I don't understand the different behavior here. Why does it seem as though the url-encoded value for an ampersand gets decoded before you actually request a specific key, but another url-encoded character, like a dollar sign, only gets decoded after you actually request that specific key?

Is this a recent change? I always thought Request.QueryString[key] returned the actual text without decoding it first. Or does it have something to do with url re-writes?

Answer 1

ASP.NET automatically calls UrlDecode() when you access a property by key index (i.e. (Request.QueryString["key"]).

If you want it encoded, just do:

HttpUtility.UrlEncode(Request.QueryString["key"]);

In terms of the ampersand specifically, that is a special case character because it is already used as a query string delimeter. URL Encoding and decoding an ampersand should always give you & for that very reason.