ASP.NET Calender Validation

Today I need to validate that a user had entered a date in an asp.net calender only to find that there were no solutions for it so for future reference, if you want a calendar validator use the following:

public class CalendarValidator : BaseValidator
{
	protected override bool ControlPropertiesValid()
	{
		return true;
	}

	protected override bool EvaluateIsValid()
	{
		var control = Parent.FindControl(ControlToValidate) as Calendar;

		if(null == control)
		{
			throw new NullReferenceException(
				string.Format(”Could not find the control with id {0} on the page”, ControlToValidate)
			);
		}

		if(DateTime.MinValue == control.SelectedDate)
		{
			return false;
		}

		return true;
	}
}