data annotation disallowing numbers only strings ASP.NET MVC C#

Question

How would one create a data annotation that only allows string that either have letters and numbers or letters only.

Basically disallow number only strings.

Right now, I have a letter only validation and I can't find out how to also allow numbers IF there are letters present in the string.

[RegularExpression(@"^[a-zA-Z]+$", ErrorMessage = "No numbers allowed in the sequence.")]

Thanks!

EDIT - Found a solution!

Basicall:

[0-9]*[A-z ]+[0-9]*

This regex works ALMOST perfectly...

It catches an error if the users enters a number-only string, but... If he adds a single space, he can get away with the string.

To prevent that little error, I simply catch any empty spaces in my POST method from my controller and add an error to the ModelState.

Thanks to @PhillipBetts for the Regex 101 link, which helped me solve this problem!

Eric Hotinger · Accepted Answer · 2015-11-02 15:29:58Z

1

I think the simplest way is to change your regular expression to \D to indicate there is at least one non-digit.

answered Nov 2, 2015 at 15:29

Eric Hotinger

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3 Comments

Raspberry Over a year ago

That didn't do the trick sadly. It doesn't seem to be picking up any value with this.

Eric Hotinger Over a year ago

@Raspberry weird - it will work fine in a Regex.Matches - you may want to play around with it a bit.

Raspberry Over a year ago

Well, what I meant is that, as soon as I enter a number, I get an error.

Phillip Morton · Accepted Answer · 2015-11-02 15:33:07Z

0

There are a bunch of resources out there to test and learn Regex. My favourite Regex 101.

It also has a library that you can search and find useful Regex. It also gives a handy explanation.

Anyway, hopefully this is what you're looking for :

^[\w ]+$

answered Nov 2, 2015 at 15:33

Phillip Morton

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2 Comments

Eric Hotinger Over a year ago

Problem is, a string like 1asdf or asdf1 should be valid. Can't use that.

Eric Hotinger Over a year ago

Yeah, he only wants to reject strings which have only numbers. A string which has both characters and numbers is fine.

Patrick Schneider · Accepted Answer · 2015-11-02 15:05:14Z

0

you should try the String contains method with your regex

https://msdn.microsoft.com/de-de/library/dy85x1sa(v=vs.110).aspx

answered Nov 2, 2015 at 15:05

Patrick Schneider

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1 Comment

Raspberry Over a year ago

Hmmm, that would imply that I would have to check the value in the controller, I am trying to find a way to get a working data annotation.

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