C#使用Data Annotations进行手动数据验证

    static void Main(string[] args)
    {
        var user = new User();
        var context = new ValidationContext(user, null, null);

        var results = new List<ValidationResult>();
        Validator.TryValidateObject(user, context, results, true);

        foreach (var validationResult in results)
        {
            Console.WriteLine(validationResult.ErrorMessage);
        }
    }

    class User
    {
        [Required]
        public string Name { get; set; }

        [Range(10, 50)]
        public int Age { get; set; }
    }

    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
    public class CountryAttribute : ValidationAttribute
    {
        public string AllowCountry { get; set; }

        public override bool IsValid(object value)
        {
            return string.Equals(value, AllowCountry);
        }

        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            if (string.Equals(value, AllowCountry))
                return ValidationResult.Success;
            else
                return new ValidationResult(string.Format("{0} 字段非法", validationContext.DisplayName), new []{ validationContext.MemberName});
        }
    }