protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
CitySqlDAO citySqlDAO = new CitySqlDAO(@"Data Source=.\SQLEXPRESS;Initial Catalog=World;Integrated Security=True");
List <string> countryCodes = citySqlDAO.GetCountryCodes().ToList();
City city = (City)validationContext.ObjectInstance;
if (!countryCodes.Contains(city.CountryCode))
{
return(new ValidationResult("Country Code does not exist. Please try again."));
}
return(ValidationResult.Success);
}