In ASP.NET, why is there UrlEncode() AND UrlPathEn

Question

In a recent project, I had the pleasure of troubleshooting a bug that involved images not loading when spaces were in the filename. I thought "What a simple issue, I'll UrlEncode() it!" But, NAY! Simply using UrlEncode() didn't resolve the problem.

The new problem was the HttpUtilities.UrlEncode() method switched spaces () to plusses (+) instead of %20 like the browser wanted. So file+image+name.jpg would return not-found while file%20image%20name.jpg was found correctly.

Thankfully, a coworker pointed out HttpUtilities.UrlPathEncode() to me which uses %20 for spaces instead of +.

WHY are there two ways of handling Url encoding? WHY are there two commands that behave so differently?

Answer 1

So in a URL you have the path and then a ? and then the parameters (i.e. http://some_path/page.aspx?parameters). URL paths encode spaces differently then the url parameters, that's why there is the two versions. For a long time spaces were not valid in a URL, but were in in the parameters.

In other words the formatting urls has changed over time. For a long time only ANSI chars could be in a URL too.

Answer 2

UrlEncode is useful for use with a QueryString as browsers tend to use a + here in place of a space when submitting forms with the GET method.

UrlPathEncode simply replaces all characters that cannot be used within a URL, such as <, > and .

Both MSDN links include this quote:

You can encode a URL using with the UrlEncode method or the UrlPathEncode method. However, the methods return different results. The UrlEncode method converts each space character to a plus character (+). The UrlPathEncode method converts each space character into the string "%20", which represents a space in hexadecimal notation. Use the UrlPathEncode method when you encode the path portion of a URL in order to guarantee a consistent decoded URL, regardless of which platform or browser performs the decoding.