相关疑难解决方法(0)

鉴于以下对象,

public class Question
{
    [Required]
    public string QuestionText { get; set; }

    [Range(1, 5)]
    public int Difficulty { get; set; }        
}

使用以下验证码

ICollection<ValidationResult> results = new List<ValidationResult>();
Question question = new Question();
ValidationContext ctx = new ValidationContext(question, null, null);
Validator.TryValidateObject(question, ctx, results);
// results.Length = 1

为什么Range属性在Required(值显然为0)时不会创建验证错误？