@Html.DropDownListFor 怎么在客户端验证
@Html.TextBoxFor(a => a.Title, new { style = "width:80%", maxlength = "80" })
可以实现在客户端验证

为什么 @Html.DropDownListFor( a => a.TypeId,(SelectList) ViewData["TypeId"],"—传达范围—")不行？

            <tr>
                <td width="15%">
                    标题：
                </td>
                <td colspan="3">@Html.TextBoxFor(a => a.Title, new { style = "width:80%", maxlength = "80" })
                    @Html.ValidationMessageFor(a => a.Title)
                </td>
            </tr>
            <tr>
                <td width="15%">
                    分类：
                </td>
                <td width="35%">
                    @Html.DropDownListFor( a => a.TypeId,(SelectList) ViewData["TypeId"],"—传达范围—")
                    @Html.ValidationMessageFor(a => a.TypeId)
                </td>
            </tr>

    [MetadataType(typeof(TaskMD))]
    public partial class Task
    {

 
    }
    public class TaskMD
    {
        [Required(ErrorMessage = "必须选择类型")]
        public int TypeId { get; set; }

        [Required(ErrorMessage = "必须设置【任务名称】")]
        public string Title { get; set; }
    }

------解决方案--------------------

引用:

@Html.TextBoxFor(a => a.Title, new { style = "width:80%", maxlength = "80" })
可以实现在客户端验证

为什么 @Html.DropDownListFor( a => a.TypeId,(SelectList) ViewData["TypeId"],"—传达范围—")不行？

用nullable ( public int？ TypeId),并且保证要在表单的里面。
保证 2个 jquery.validate.unobtrusive.js/jquery.validate.js 也引用了

    public class TaskMD
    {
        [Required(ErrorMessage = "必须选择类型")]
        public int？ TypeId { get; set; }
 
        [Required(ErrorMessage = "必须设置【任务名称】")]
        public string Title { get; set; }
    }