MVC4数据注释无法对null引用执行运行时绑定

Question

这是我第一次尝试使用数据注释，在尝试测试验证时，我一直收到上面的错误。

我的模型看起来像：

    public class SupplierValidationModel
{
    [Display(Name = "Company Name:")]
    [Required(ErrorMessage = "Company Name is Required")]
    public string Name { get; set; }
    [Display(Name = "Company Address:")]
    [Required(ErrorMessage = "Company Address is Required")]
    public string Address { get; set; }
    [Display(Name = "Company City:")]
    [Required(ErrorMessage = "Company City is Required")]
    public string City { get; set; }
    [Display(Name = "Company State:")]
    [Required(ErrorMessage = "Company State is Required")]
    public string State { get; set; }
    [Display(Name = "Company Zip:")]
    [Required(ErrorMessage = "Company Zip is Required")]
    public string Zip { get; set; }
    [Display(Name = "Company Phone:")]
    [Required(ErrorMessage = "Company Phone is Required")]
    [RegularExpression(@"(((d{3}) ?)|(d{3}-))?d{3}-d{4}", ErrorMessage = "A Valid Phone Number is Required")]
    public string Phone { get; set; }
    [Display(Name = "Contact Name:")]
    [Required(ErrorMessage = "Contact Name is Required")]
    public string ContactName { get; set; }
    [Display(Name = "Contact E-Mail:")]
    [Required]
    [EmailAddress(ErrorMessage = "Valid E-Mail Required")]
    public string ContactEmail { get; set; }
    [Display(Name = "Contact Phone:")]
    [Required]
    [RegularExpression(@"(((d{3}) ?)|(d{3}-))?d{3}-d{4}", ErrorMessage = "A Valid Phone Number is Required")]
    public string ContactPhone { get; set; }
    [Display(Name = "Added By:")]
    [Required(ErrorMessage = "Added By Must Be Entered")]
    public string AddedBy { get; set; }
}

我的观点是这样的；

@model SupplierValidationModel
@using (Html.BeginForm("InsertSupplier", "Admin", FormMethod.Post))
    {
        @Html.ValidationSummary(false)
        <table>
            <tr>
                <td>@Html.LabelFor(m => m.Name)</td>
                <td>@Html.TextBoxFor(m => m.Name) @Html.ValidationMessageFor(m=>m.Name)</td>
                <td>@Html.LabelFor(m => m.Address)</td>
                <td>@Html.TextBoxFor(m => m.Address) @Html.ValidationMessageFor(m => m.Address)</td>
            </tr>
            <tr>
                <td>@Html.LabelFor(m => m.City)</td>
                <td>@Html.TextBoxFor(m => m.City) @Html.ValidationMessageFor(m => m.City)</td>
                <td>@Html.LabelFor(m => m.State)</td>
                <td>@Html.DropDownListFor(m => m.State, StateList.States) @Html.ValidationMessageFor(m => m.State)</td>
            </tr>
            <tr>
                <td>@Html.LabelFor(m => m.Zip)</td>
                <td>@Html.TextBoxFor(m => m.Zip) @Html.ValidationMessageFor(m => m.Zip)</td>
                <td>@Html.LabelFor(m => m.Phone)</td>
                <td>@Html.TextBoxFor(m => m.Phone) @Html.ValidationMessageFor(m => m.Phone)</td>
            </tr>
            <tr>
                <td>@Html.LabelFor(m => m.ContactName)</td>
                <td>@Html.TextBoxFor(m => m.ContactName) @Html.ValidationMessageFor(m => m.ContactName)</td>
                <td>@Html.LabelFor(m => m.ContactEmail)</td>
                <td>@Html.TextBoxFor(m => m.ContactEmail) @Html.ValidationMessageFor(m => m.ContactEmail)</td>
            </tr>
            <tr>
                <td>@Html.LabelFor(m => m.ContactPhone)</td>
                <td>@Html.TextBoxFor(m => m.ContactPhone) @Html.ValidationMessageFor(m => m.ContactPhone)</td>
                <td>@Html.LabelFor(m => m.AddedBy)</td>
                <td>@Html.TextBoxFor(m => m.AddedBy) @Html.ValidationMessageFor(m => m.AddedBy)</td>
            </tr>
            <tr>
                <td colspan="4" align="right"><input type="submit" value="Add Supplier" /></td>
            </tr>
        </table>
    <input type="hidden" name="userId" value="@ViewBag.Employee.AccountName" />
    }

最后，我的行动是；

        [HttpPost]
    public ActionResult InsertSupplier(SupplierValidationModel model)
    {
       // string userName = coll["userId"].ToString();            
        if (ModelState.IsValid)
        {
            DataOps.InsertSupplier(model);
            return View();
        }else{
            ViewData["Valid"] = false;
            //return RedirectToAction("SupplierInfo", "Admin", new {employeeAcct = userName });
            return View(model);
        }
    }

无论怎样，当我再次返回View（）并只想加载带有相关错误消息的表单时，我都会收到无法执行运行时错误。

我已经学习了很多教程，所有的东西都在ModelState中正确加载，但它是无效的，但从未渲染过表单。

Answer 1

可能@ViewBag。隐藏字段中的员工为空。如果您在GET操作中加载了它，那么您也必须在POST上加载。