im using code as below to check for the URL validation:
public static bool CheckURLValid(string strURL)
{
Uri uriResult;
return Uri.TryCreate(strURL, UriKind.Absolute, out uriResult) && uriResult.Scheme == Uri.UriSchemeHttp;
}
The result as below should show all as true, but somehow it has its own pattern to validate the url:
false: google.com
true: http://www.google.com
true: https://stackoverflow.com/questions/ask
im using c#, how to enhance this checking url validation to be more accurate?
Answers:
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Method 1
Your CheckURLValid is returning exactly what you have told it to.
To return True on all 4 URLs here are the issues
false: google.com
This is a relative url and you have specified UriKind.Absolute which means this is false.
This is an httpS (Secure) url and your method says
&& uriResult.Scheme == Uri.UriSchemeHttp;
which will limit you to only http addresses (NON secure)
To get the results you are wanting you will need to use the following method:
public static bool CheckURLValid(string strURL)
{
Uri uriResult;
return Uri.TryCreate(strURL, UriKind.RelativeOrAbsolute, out uriResult);
}
An alternative is to just use
Uri.IsWellFormedUriString(strURL, UriKind.RelativeOrAbsolute);
and not re implement functionality that all ready exists. If you wanted to wrap it it your own CheckUrlValid I would use the following:
public static bool CheckURLValid(string strURL)
{
return Uri.IsWellFormedUriString(strURL, UriKind.RelativeOrAbsolute); ;
}
The main problem is that most strings are valid relative URL’s so I would avoid using UriKind.RelativeOrAbsolute as google.com is an invalid url. Most web browsers silently add HTTP:// to the string to make it a valid url. HTTP://google.com is a valid url.
Method 2
Not sure if I’m missing something here, but just so others don’t waste their time with Uri.IsWellFormedUriString, note that the following test fails:
[TestMethod]
public void TestURLValidation()
{
bool result = Uri.IsWellFormedUriString("bad", UriKind.RelativeOrAbsolute);
Assert.IsFalse(result);
}
I.e., the prescribed answer will consider “bad” as a valid address. I believe that’s not the behavior most users are after.
Method 3
You can try
var isUrl = Uri.IsWellFormedUriString(strURL, UriKind.RelativeOrAbsolute);
It returns true on all four strings you wrote in your question.
Method 4
This is the best solution without using Regex:
(note that for example using only “IsWellFormedUriString” will return true for “//”)
public static bool IsValidUrl(string url)
{
if (url == null)
{
return false;
}
try
{
Uri uriResult = new Uri(url);
return Uri.IsWellFormedUriString(url, UriKind.RelativeOrAbsolute);
}
catch
{
return false;
}
}
For unit testing you can check the link where my function got nice results.
Method 5
I got it working by writing a small helper method that uses Regex to validate the url.
The following URL’s pass:
google.com
www.google.com
It fails on:
www.google.com/a bad path with white space/
Below is the helper method I created:
public static bool ValidateUrl(string value, bool required, int minLength, int maxLength)
{
value = value.Trim();
if (required == false && value == "") return true;
if (required && value == "") return false;
Regex pattern = new Regex(@"^(?:http(s)?://)?[w.-]+(?:.[w.-]+)+[w-._~:/?#[]@!$&'()*+,;=.]+$");
Match match = pattern.Match(value);
if (match.Success == false) return false;
return true;
}
This allows users to input any valid url, plus it accounts for bad url paths with white space which is exactly what I needed. I hope this helps someone
All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0