Regular expression data validation attribute does not return error message

Question

I have my model:

[RegularExpression("[0-9]+", ErrorMessage = "GroupId must be a number")]
public int? GroupId { get; set; }

And WebApi application. I expect controller to return error message like this:

{
   "$id": "1",
   "Message": "GroupId must be a number"
}

For example, when I have Required attribute, it works just fine:

[Required]
[StringLength(64, MinimumLength = 1, ErrorMessage = "Name must be between 1 and 64 characters long.")]
public string Name { get; set; }

{
   "$id": "1",
   "Message": "The Name field is required."
}

And ReqularExpression just does not work.

I have also tried:

[RegularExpression(@"^[0-9]+$", ErrorMessage = "GroupId must be a number")]
[RegularExpression("[0-9]+", ErrorMessage = "GroupId must be a number")]
[RegularExpression(@"^([0-9]+)$", ErrorMessage = "GroupId must be a number")]

I have custom ActionFilterAttribute on my WebApi controller. And it creates response using HttpActionContext actionContext.modelState.

modelState.Values[0].Errors[0].Exeption value is null for Regex Attribute, and the Exeption text is "Could not convert string to integer: Path 'GroupId '.

Could someone tell me what is wrong with this?

PS

I create custom validation attribute:

protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            if (value != null)
            {
                int parseResult;

                if (!int.TryParse(value.ToString(), out parseResult))
                    return new ValidationResult("Value must be a number");
            }

            return ValidationResult.Success;
        }

Now object value comes null if non-numeric value was specified.

Also I tried DataAnnotationsExtensions package, it did not help.

P.S.S.

Apparently, it because model binding takes place before validation. You can find more information here Server side validation of int datatype

Regular expression data validation attribute does not return error message

0 Answers0