How to validate a valid GUID Value in C#

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How to validate a valid GUID Value in C#

VIA Scott Galloway's Blog

In this implementation you pass in a Guid as an 'out' parameter along with the string you want to test - it then fills in the Guid and returns true / false depending on whether the Guid was valid...

private static Regex isGuid = new Regex(@"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}(\}){0,1}$", RegexOptions.Compiled);

internal static bool IsGuid(string candidate, out Guid output)

{

bool isValid = false;

output=Guid.Empty;

if(candidate!=null)

{

if (isGuid.IsMatch(candidate))

{

output=new Guid(candidate);

isValid = true;

}

return isValid;

}

This is very useful in other Microsoft Products like Microsof Content Management Server/SharePoint where you use GUID quite frequently in the API Calls.

Print | posted on Friday, May 20, 2005 5:20 AM | Filed Under [ ASP.NET ]

Feedback

# re: How to validate a valid GUID Value in C#

Thank you very much for sharing your code. It has been a great help.

1/21/2006 7:17 AM | Frank Gennaro

# re: How to validate a valid GUID Value in C#

Microsoft's Regex stuff is really poorly documented, it seems. Thanks for this.

9/27/2006 1:54 PM | Pete

# re: How to validate a valid GUID Value in C#

Thanks for the great code!

1/23/2007 5:01 AM | Kirkov

# re: How to validate a valid GUID Value in C#

Thanks! This helped me. Not sure why they don't have a TryParse for Guids.

2/28/2007 10:10 PM | Mike

# re: How to validate a valid GUID Value in C#

Thank you so much. Exactly what I'm looking for

3/18/2007 10:58 PM | Frank

# re: How to validate a valid GUID Value in C#

fix the code for this kind of input
"{e73a048d- bf27-4f12-9731-8b2076e8891f"

4/12/2007 12:54 AM | Jagdish Vasani

# re: How to validate a valid GUID Value in C#

sry there was an extra space after the 1st dash in my earlier post -->

fix the code for this kind of input
"{e73a048d- bf27-4f12-9731-8b2076e8891f"

its should be
"{e73a048d-bf27-4f12-9731-8b2076e8891f"

4/12/2007 12:57 AM | Jagdish Vasani

# re: How to validate a valid GUID Value in C#

Why the hell my comment had a swastika icon next to it???

2/11/2008 5:35 AM | Ariel

# re: How to validate a valid GUID Value in C#

It's probably an auto-generated ip address to icon. Every ip has his unique icon.

Funny though

>Why the hell my comment had a swastika icon next to it???

2/21/2008 5:03 PM | K

# re: How to validate a valid GUID Value in C#

My thanks also for this code. I wonder what my graphic will look like?

3/18/2008 10:13 AM | Rory Becker

# re: How to validate a valid GUID Value in C#

Thanks for the code

4/12/2008 4:05 PM | D

# re: How to validate a valid GUID Value in C#

Good stuff, thanks!

6/27/2008 2:21 PM | Dmitriy K

# re: How to validate a valid GUID Value in C#

Thank you so much,
There is another silliy solution without RegEx for that.

public static bool IsGuid(string guidString)
{
bool bResult=false;
try
{
Guid g = new Guid(guidString);
bResult=true;
}
catch
{
bResult=false;
}

return bResult;
}

If the guidString is not valid, Guid class throws an error.

9/23/2008 4:58 PM | Reza

# re: How to validate a valid GUID Value in C#

askl;ja awerj pojasdf kl;jaeiopuawr[iuoaer'kl asf'klasdfopw]tiotklj a;lksfa wpoeir adjklj;poiqwer

9/26/2008 4:55 PM | qwaer

# re: How to validate a valid GUID Value in C#

cool. I want i dyn image too :)

11/30/2008 6:16 PM | allegro

# re: How to validate a valid GUID Value in C#

This is great though it is doing two things 1. Validating 2. Converting string to Guid. I would rather do just the check which removes the coupling:

private static readonly Regex guidPattern = new Regex(@"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}(\}){0,1}$", RegexOptions.Compiled);

public static bool IsGuid(this string input)
{
return guidPattern.IsMatch(input);
}

then create the guid instance as needed, SRP and all that.

12/19/2008 9:58 AM | madsnakes

# re: How to validate a valid GUID Value in C#

Very nice, thanks for posting.

1/8/2009 6:12 PM | Mike

# re: How to validate a valid GUID Value in C#

This code has a bug, allowing unmatched curly braces.

You can pass in a string like:

{1102F615-9508-41EF-9699-B517C09D5FEE

and the method will return true.

2/18/2009 8:44 AM | Neil Pullinger

# re: How to validate a valid GUID Value in C#

Further to my comment, you could change the regex to enforce the use of curly braces. Or change it not to have curly braces at all. You could pass in an extra parameter to the method to to switch between "must have both braces" or "must not have any braces".

2/18/2009 9:05 AM | Neil Pullinger

# re: How to validate a valid GUID Value in C#

I have a question and I know this is an OLD thread. However, if you have a variable that is already of type guid, your regex does not verify it is not an empty guid. An empty guid is also a properly formatted guid.

Do you have a regex that matches a valid guid that isn't an empty guid? I have modified one to find an empty guid, but I cannot seem to invert it.

Thank you

2/18/2009 9:54 AM | jason

# re: How to validate a valid GUID Value in C#

Thanx dude, you save me from so much work trying to figure this out myself!

2/26/2009 8:13 AM | Eben

# re: How to validate a valid GUID Value in C#

I wanna know how to create a GUID :-((((

4/28/2009 9:17 AM | Well

# re: How to validate a valid GUID Value in C#

Excellent! I can't believe they left this out

5/4/2009 5:24 AM | Jason

# re: How to validate a valid GUID Value in C#

to validate an empty guid just check for guid.empty.

5/27/2009 7:40 PM | Daniel

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