I want to make a rule with Fluent Validation that checks: if this field contains a Credit Card number then it is invalid (because it contains sensitive data)

Seems easy.

Fluent Validation provides CreditCard() check, but it's the opposite of what i'm trying to do, i searched if there is some kind of negation, like .Not().CreditCard() or .NotMatch(), but i couldn't find.

There is the idea of making a RegExp that will not match only when the field contains a valid credit card, but it seems very unintuitive and unreadable, i wander if there is a more straight forward solution.

CodePudding user response：

CreditCardValidator is given for a purpose so that we can avoid saving/processing invalid CreditCard. but with your requirement it seems you would allow to save/process invalid creditcard but will block user for giving valid data.

I am not able to get what is real use case here. could please clarify your usecase.

Update:

you could do something like this.

public class MyCreditCardValidator<T> : CreditCardValidator<T>
{
    public override bool IsValid(ValidationContext<T> context, string value)
    {
        bool validCreditCard = base.IsValid(context, value);

        // for my case i want invalid credit card
        return !validCreditCard;
    }

    protected override string GetDefaultMessageTemplate(string errorCode)
    {
        return "field contains credit card";
    }
}

and add extension method like

public static class CustomerValidatorExtensions
{
        public static IRuleBuilderOptions<T, string> NotACreditCard<T>(this IRuleBuilder<T, string> ruleBuilder)
        {
            return ruleBuilder.SetValidator(new MyCreditCardValidator<T>());
        }
}

and call like this

public CustomerValidator()
{
   RuleFor(a => a.Notes).NotACreditCard();
}

now when you provide valid creditcard in the notes field it will fail the validation and return your the error

Hope this helpful.