CheckSchemeName fail on url with multiple prefix

Question

I have this url: turnerstadium.co.il, I'm trying to check if the scheme is correct so I did:

if (!Uri.CheckSchemeName(link))
{
   link = "http://" + link;
}

the problem is that CheckSchemeName return true, so when I do this:

var url = new Uri(link);

I get:

Invalid URI: The format of the URI could not be determined

how can I fix that?

Che [This](https://stackoverflow.com/questions/17968426/changing-the-scheme-of-system-uri) — NaDeR Star, Jan 11 '19 at 15:16

score 0 · Accepted Answer · answered Jan 11 '19 at 15:22

This is the code of CheckSchemeName method.

public static bool CheckSchemeName(string schemeName)
{
  if (schemeName == null || schemeName.Length == 0 || !Uri.IsAsciiLetter(schemeName[0]))
    return false;
  for (int index = schemeName.Length - 1; index > 0; --index)
  {
    if (!Uri.IsAsciiLetterOrDigit(schemeName[index]) && schemeName[index] != '+' && (schemeName[index] != '-' && schemeName[index] != '.'))
      return false;
  }
  return true;
}

From the remarks section of Uri.CheckSchemeName:

The scheme name must begin with a letter and must contain only letters, digits, and the characters ".", "+", or "-".

So as you can see, this method only checks if the string you are passing meets these requirements.

If you only want to check if the string starts with "http://" and append it in case it is not there, one of the possible solutions would be:

  if (!link.StartsWith("http://"))
  {
    link = "http://" + link;
  }

Otherwise I recommend reading this.

score -1 · Answer 2 · answered Jan 11 '19 at 15:13

Check UriBuilder at: https://learn.microsoft.com/en-us/dotnet/api/system.uribuilder?view=netframework-4.7.2

It has constructors to add the scheme if the scheme is not present.

var url = new UriBuilder("siteUrl.com").Uri.ToString();

This will return "http://siteUrl.com"

CheckSchemeName fail on url with multiple prefix

2 Answers2