Question

I’m using mvc. So I want to validate user input number is 7 digit.

So I wrote a class.

 public class StduentValidator : AbstractValidator<graduandModel>
    {
        public StduentValidator(ILocalizationService localizationService)
        {                          
           RuleFor(x => x.student_id).Equal(7)
               .WithMessage(localizationService
                    .GetResource("Hire.graduand.Fields.student_id.Required"));                   
        }

But it is not working.
How to validate 7 digit numbers?

Answer 1

Since you’re using FluentValidation, you want to use the .Matches validator to perform a regular expression match.

RuleFor(x => x.student_id).Matches("^\d{7}$")....

Another option is to do something like this (if student_id is a number):

RuleFor(x => x.student_id).Must(x => x > 999999 && x < 10000000)...

Or, you could use the GreaterThan and LessThan validators, but the above easier to read. Also note that if a number is something like 0000001 then the above won’t work, you’d have to convert it to a string with 7 digits and use the technique below.

if student_id is a string, then something like this:

int i = 0;
RuleFor(x => x.student_id).Length(7,7).Must(x => int.TryParse(x, out i))...