MVC模型验证扩展一个类似Range的日期验证，求高手指点

Question

DatetimeRange类似于Range可以指定日期范围，也可传入int类型的参数

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;namespace System.ComponentModel.DataAnnotations
{
    /// <summary>
    /// 关于返回值形式的枚举
    /// </summary>
    public enum DateTimeRangeType
    {        /// <summary>
        /// 年数
        /// </summary>
        Year,
        /// <summary>
        /// 月数
        /// </summary>
        Month,
        /// <summary>
        /// 天数
        /// </summary>
        Day,
        /// <summary>
        /// 分钟
        /// </summary>
        Minute
    }
    /// <summary>
    /// 时间范围限制(相对当前时间)
    /// </summary>
    public class DateTimeRange : ValidationAttribute
    {
        private DateTimeRangeType _type = DateTimeRangeType.Day;
        /// <summary>
        /// 可选
        /// </summary>
        public int Min { get; set; }
        /// <summary>
        /// 可选
        /// </summary>
        public int Max { get; set; }
        /// <summary>
        /// 可选 默认DateTimeRangeType
        /// </summary>
        public DateTimeRangeType Type
        {
            get
            {
                return _type;
            }
            set
            {
                _type = value;
            }
        }        /*
        public static bool DateTimeRangeAttribute(Type Type,int minDateTime,int maxDateTime)
        {
            return true;
        }*/
        /// <summary>
        /// ErrorMessage = "{0}必须在{1}和{2}之间"
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public override bool IsValid(object value)
        {
            if (!(value is DateTime))
            {
                throw new Exception("字段必须为时间类型");
            }
            
            
            var dateValue = (DateTime)value;
            //if (String.IsNullOrEmpty(ErrorMessage))
                //ErrorMessage = "{0}必须在{min}和{max}之间";
            if (Min != 0)
            {
                DateTime minDateTime = GetDateTime(_type, Min);
                //ErrorMessage = ErrorMessage.Replace("{min}", _type == DateTimeRangeType.Minute ? minDateTime.ToString() : minDateTime.ToShortDateString());
                if (dateValue < minDateTime)
                    return false;
            }
            if (Max != 0)
            {
                DateTime maxDateTime = GetDateTime(_type, Max);
                //ErrorMessage = ErrorMessage.Replace("{max}", _type == DateTimeRangeType.Minute ? maxDateTime.ToString() : maxDateTime.ToShortDateString());
                if (dateValue > maxDateTime)
                    return false;
            }            return true;
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="value"></param>
        /// <param name="validationContext"></param>
        /// <returns></returns>
        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            validationContext.ObjectType.GetProperty("").GetValue(validationContext.ObjectInstance, null);
            return base.IsValid(value, validationContext);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public override string FormatErrorMessage(string name)
        {
            return base.FormatErrorMessage(name);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="type"></param>
        /// <param name="diff"></param>
        /// <returns></returns>
        private DateTime GetDateTime(DateTimeRangeType type, int diff)
        {            switch (type)
            {
                case DateTimeRangeType.Minute:
                    {
                        return DateTime.Now.AddMinutes(diff);
                    }
                case DateTimeRangeType.Day:
                    {
                        return DateTime.Now.Date.AddDays(diff);
                    }
                case DateTimeRangeType.Month:
                    {
                        return DateTime.Now.Date.AddMonths(diff);
                    }                case DateTimeRangeType.Year:
                    {
                        return DateTime.Now.Date.AddYears(diff);
                    }            }
            return DateTime.Now;
        }    }
}