Custom number validation not working properly when value isn't a number

Question

I've got custom validation that checks another field, and then determines if the field in question is within a certain number range. It works fine whenever the user enters a number. However, if the user passes in a non-number, this non-number (the value parameter) doesn't get passed to the validation. Instead, null is passed to the validation. I'd rather have the number with the commas be passed in. Instead, the user is presented with a cryptic "The value XXX is not valid for XXX which isn't helpful. I've also got [Required] and [Numeric] data annotations on this field. These usually catch any issues. However, if the user enters a valid number with a comma, the value won't get passed to my custom validation. I'm not sure where the issue is happening. Any thoughts? I've tried stripping out the commas via javascript, but the value being passed to my custom validation is still null. Here's my custom validation that is being called:

public sealed class RequiresRangeAmount : ValidationAttribute
{
    public RequiresRangeAmount(string property)
    {
        Property = property;
    }

    public string Property { get; set; }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var property = validationContext.ObjectType.GetProperty(Property);

        if (property != null)
        {
            var loanSubType = (int)property.GetValue(validationContext.ObjectInstance, null);

            if (loanSubType == LoanSubTypeConstants.Visa|| loanSubType == LoanSubTypeConstants.Visa2)
            {
                var valueConverted = Convert.ToDecimal(value);
                if (valueConverted < 5000 || valueConverted > 75000)
                {
                    return new ValidationResult(ErrorMessage);
                }
            }
        }

        return null;
    }
}

Here is is being used:

[Required]
[Numeric]
[RequiresRangeAmount("LoanSubType", ErrorMessage = "A VISA must be in XXX range.")]
[DisplayName("Requested Loan Amount")]
public decimal? RequestedAmount { get; set; }

Front-end to strip the commas out doesn't help:

$("#mainForm").submit(function() {
    var strippedCommasAmount = $("#RequestedAmount").val().replace(/,/g, '');
    $("#RequestedAmount").val(strippedCommasAmount);
});

Please show us a complete example and the error message you are receiving. — Jasen, Nov 14 '18 at 17:44
I'm not sure what else you want? When I include a comma, the custom validation reads the value passed in as null. When I don't include a comma, the value successfully passes into the custom validation. — The Vanilla Thrilla, Nov 14 '18 at 18:39
The comma would make the value a string then you would have binding issues. — Jasen, Nov 14 '18 at 19:14
But I even tried stripping the commas out on the front-end and this didn't resolve it. I've added that code to show. — The Vanilla Thrilla, Nov 14 '18 at 19:16

score 0 · Answer 1 · answered Nov 14 '18 at 20:13

don't know if it helps, but I have that function I now use in all of my projects :

public static double DoubleParseAdvanced(this string strToParse, char decimalSymbol = '.')
        {
            string tmp = Regex.Match(strToParse, @"([-]?[0-9]+)([\s])?([0-9]+)?[." + decimalSymbol + "]?([0-9 ]+)?([0-9]+)?").Value;

            if (tmp.Length > 0 && strToParse.Contains(tmp))
            {
                var currDecSeparator = System.Windows.Forms.Application.CurrentCulture.NumberFormat.NumberDecimalSeparator;

                tmp = tmp.Replace(".", currDecSeparator).Replace(decimalSymbol.ToString(), currDecSeparator);
                return double.Parse(tmp);
            }

            return double.NegativeInfinity;
        }

1st, it works whatever the culture of computer(500.5 or 500,5)

2nd if the user types something that is not number, you just return NegativeInfinite, so you just need to check if returned value is not equal to NegativeInfinity to know if value is a correct one, or not.

Custom number validation not working properly when value isn't a number

1 Answers1