MVC Validation make RegularExpression numeric only on string field

Question

I have the following property in my view model:

[Required]
[MaxLength(12)]
[MinLength(1)]
[RegularExpression("[^0-9]", ErrorMessage = "UPRN must be numeric")]
public string Uprn { get; set; }

Regardless of Uprn being a string, I want to throw a validation error if there is anything other than numbers entered into the Uprn box on page submit.

With the above, I am getting the error "UPRN must be numeric" whether its a string or int

What's going on here?

Is your property an array? It is just a string in your code snippet? — Ashley Medway, May 29 '15 at 14:29
To clarify why the regex is wrong, `^` inside `[]` means *not* - so you're saying: allow anything *except numbers*. — freedomn-m, Jul 05 '17 at 08:41

score 52 · Accepted Answer · answered May 29 '15 at 14:33

The regular expression is wrong. Replace it with:

[Required]
[MaxLength(12)]
[MinLength(1)]
[RegularExpression("^[0-9]*$", ErrorMessage = "UPRN must be numeric")]
public string Uprn { get; set; }

Don't forget to include:

@Scripts.Render("~/bundles/jqueryval")

in your view for the jquery validation

codeape · Answer 2 · 2015-05-29T14:43:48.200

9

Or you could do the length validation in the regexp:

[Required]
[RegularExpression("^[0-9]{1,12}$", ErrorMessage = "...")]
public string Uprn { get; set; }

Here's the regex visualized:

Regular expression visualization

Debuggex Demo

edited May 29 '15 at 14:43

answered May 29 '15 at 14:36

codeape

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This way you would only have one error message, separated out you can specify different error messages per condition :) – Ashley Medway May 29 '15 at 14:59

score 6 · Answer 3 · answered May 29 '15 at 14:36

The RegEx should be ^[0-9]*$.

I.E.

The property should look like:

[Required]
[MaxLength(12)]
[MinLength(1)]
[RegularExpression("^[0-9]*$", ErrorMessage = "UPRN must be numeric")]
public string Uprn { get; set; }

See working example.

I'm sure you already have jQuery referenced but make sure jQuery validate and Microsoft validate scripts are included.

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>

<script src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.11.1/jquery.validate.min.js"></script>

<script src="//ajax.aspnetcdn.com/ajax/mvc/4.0/jquery.validate.unobtrusive.min.js"></script>

score 3 · Answer 4 · answered May 30 '15 at 11:34

I suggest you use either:

[RegularExpression("\d*", ErrorMessage = "UPRN must be numeric")]

*note that it will accept empty if you remove [Required] and [MinLength(1)]

or use the following:

[RegularExpression("\d+", ErrorMessage = "UPRN must be numeric")]

which will only accept one more digits

you can test your regular expressions here: https://regex101.com/

MVC Validation make RegularExpression numeric only on string field

4 Answers4

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