XdCxRhDW/XdCxRhDw.Dto/Attribute/FileMustExistAttribute.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace XdCxRhDw.Dto.Attribute
{
    /// <summary>
    /// 文件存在性验证,会验证本地文件是否存在
    /// </summary>
    public class FileMustExistAttribute : ValidationAttribute
    {
        /// <summary>
        /// 
        /// </summary>
        public FileMustExistAttribute()
        {
        }
        /// <summary>
        /// 文件验证
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        /// <exception cref="Exception"></exception>
        public override bool IsValid(object value)
        {
            if (value.GetType() != typeof(string))
            {
                throw new Exception($"{nameof(FileMustExistAttribute)}只能用于string类型!");
            }
            string fileName = value.ToString();
            if(string.IsNullOrWhiteSpace(fileName) ) 
            {
                ErrorMessage= "字段 {0} 值不能为空";
                return false;
            }
            if (fileName.Contains("\\") || fileName.Contains("/"))
            {
                ErrorMessage = $"文件[{value}]格式错误,必须是上传后返回的名称";
                return false;
            }
            ErrorMessage = $"文件[{value}]不存在,请先上传";
            string localFile = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "wwwroot", fileName);
            return File.Exists(localFile);
        }
    }
}