non-nullable type 'System.DateTime' , ASP.NET MVC

Question

I have a registration page, and because of content issues we have to request and enforce applicants giving a birthdate. So it stands to reason that this field cannot be null.

Answer 1

Have the birthdate parameter be a nullable DateTime, i.e., DateTime?, then check if it is null, set a model error, and rerender the view with the error when it is null.

[CaptchaValidator]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Register(string name, string email, string password, string validation, bool agreement, DateTime? birthdate)
{
    ValidateRegistration( name, email, password, validation, agreement, birthdate );           
    if (ModelState.IsValid)
    {
    }
    return View();
}

private bool ValidateRegistration(string name, string email, string password, string validation, DateTime? birthdate)
{
     if (!birthdate.HasValue)
     {
         this.ModelState.AddModelError( "birthdate", "You must supply a birthdate." );
     }

     ...