Question

Firstly, this seems like something that should have been asked before, but I cannot find anything that answers my question.

A basic overview of my task is to render an anchor link on a web page which is based on a user defined web address. As the address is user defined this could be in any format, for example:

• http://www.example.com
• https://www.example.com
• http://www.example.com
• example.com

What I need to do with this value is to set it as the href property of an anchor tag. Now, the problem is that (in Chrome at least) only the first two examples will work due to the fact they are recognised as absolute URL paths. The last two examples will redirect to the same domain (i.e. treated as relative paths)

So the ultimate question is: What is the best way to format these values to ensure a consistent absolute path is used? I could check for http/https and add it if missing, but I was hoping there might be an out of the box .Net class that would be more reliable.

In addition, as this is a user defined value, it could be complete junk anyway so a function to validate the URL would be a nice bonus too.

Answer 1

We ran into this problem a few months back, and needed a consistent way of ensuring the URLs were absolute. We also wanted a way of removing http(s):// for displaying the URL on the web page.

I came up with this function:

public static string FormatUrl(string Url, bool IncludeHttp = null)
{

    Url = Url.ToLower();

    switch (IncludeHttp) {
        case true:
            if (!(Url.StartsWith("http://") || Url.StartsWith("https://")))
                Url = "http://" + Url;
            break;
        case false:
            if (Url.StartsWith("http://"))
                Url = Url.Remove(0, "http://".Length);
            if (Url.StartsWith("https://"))
                Url = Url.Remove(0, "https://".Length);
            break;
    }

    return Url;

}

I know you’re after an “out of the box” library, but this may be of some help.

I think the problem with an “out of the box” solution would be that the function won’t know whether the URL should be http:// or https://. With my function I’ve made an assumption that its going to be http://, but for some URLs you need https://. If Microsoft were to build something like this into the framework, it would be buggy from the start.