.Net 使用特性方式验证参数

重点：

1、服务端主要引用 System.ComponentModel.DataAnnotations

2、客户端主要引用 jquery.validate.min.js 和 jquery.validate.unobtrusive.min.js（当然jquery.js必须是前提）

上代码

/// <summary>
    /// 用户
    /// </summary>
    public class Member
    {
        [Required(ErrorMessage ="用户名不能为空")]
        [MaxLength(16,ErrorMessage ="用户名最多为16位")]
        [Display(Name ="用户名")]
        public string UserName { get; set; }

        [Required(ErrorMessage ="密码不能为空")]
        [MinLength(6,ErrorMessage ="密码最少为6位")]
        [MaxLength(32,ErrorMessage ="密码最多为32位")]
        [Display(Name ="密码")]
        public string Password { get; set; }
    }

@{
    Layout = null;
}
@{
    ViewData["Title"] = "登录";
}
@model AttributeDemo.Models.Member
<h1>Add</h1>

@using (Html.BeginForm("Login", "Home", FormMethod.Post, new { @id = "ajaxPostForm", @class = "form-horizontal", enctype = "multipart/form-data" }))
{

    @Html.TextBoxFor(a => a.UserName, new { @class = "input form-control" })
    @Html.ValidationMessageFor(a => a.UserName)
    @Html.TextBoxFor(a => a.Password, new { @class = "input form-control" })
    @Html.ValidationMessageFor(a => a.Password)
    <button id="btnSave">提交</button>
}
<script src="~/lib/jquery/dist/jquery.min.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.min.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.min.js"></script>总结：

/// <summary>
        /// 登录
        /// </summary>
        /// <param name="member"></param>
        /// <returns></returns>
        [HttpPost]
        public IActionResult Login(Member member)
        {
            if (ModelState.IsValid)
            {
                //登录逻辑
                return Json("登录成功");
            }
            else 
            {
                //模糊化错误信息提示
                return Json("参数验证不通过");
                //精确错误信息提示（返回第一遍历到的错误信息）
                //foreach (var key in ModelState.Keys)
                //{
                //    var modelstate = ModelState[key];
                //    if (modelstate.Errors.Any())
                //    {
                //        return Json(modelstate.Errors.FirstOrDefault().ErrorMessage);
                //    }
                //}
            }
        }

优点：使用特性方式验证参数比传统逐条手写验证更优雅，前端和后端会进行双重校验，更便于扩展

缺点：前端验证依赖Razor，如果使用vue等前端框架也需要单独再写参数验证

总结：总体来说，优点是远远大于缺点的，是个好东西