How to valid DateofBirth using fluent Validation in C# if it exceeds current year?

To specify a validation rule for a particular property, call the RuleFor method, passing a lambda expression that indicates the property that you wish to validate

RuleFor(p => p.DateOfBirth)

To run the validator, instantiate the validator object and call the Validate method, passing in the object to validate.

ValidationResult results = validator.Validate(person);

The Validate method returns a ValidationResult object. This contains two properties

IsValid - a boolean that says whether the validation suceeded.

Errors - a collection of ValidationFailure objects containing details about any validation failures

Example 1

static void Main(string[] args) {
   List errors = new List();

   PersonModel person = new PersonModel();
   person.FirstName = "TestUser";
   person.LastName = "TestUser";
   person.AccountBalance = 100;
   person.DateOfBirth = DateTime.Now.Date.AddYears(1);

   PersonValidator validator = new PersonValidator();

   ValidationResult results = validator.Validate(person);

   if (results.IsValid == false) {
      foreach (ValidationFailure failure in results.Errors){
         errors.Add(failure.ErrorMessage);
      }
   }

   foreach (var item in errors){
      Console.WriteLine(item);
   }
   Console.ReadLine();

   }
}

public class PersonModel {
   public string FirstName { get; set; }
   public string LastName { get; set; }
   public decimal AccountBalance { get; set; }
   public DateTime DateOfBirth { get; set; }
}

public class PersonValidator : AbstractValidator{
   public PersonValidator(){
      RuleFor(p => p.DateOfBirth)
      .Must(BeAValidAge).WithMessage("Invalid {PropertyName}");
   }

   protected bool BeAValidAge(DateTime date){
      int currentYear = DateTime.Now.Year;
      int dobYear = date.Year;

      if (dobYear <= currentYear && dobYear > (currentYear - 120)){
         return true;
      }

      return false;
   }
}

Output

Invalid Date Of Birth