ASP.NET MVC 5项目中的不可否认类型的NULL输入

Question

i在模型中具有不可自然的属性。如果Model State IsInvalid提交表单时，我希望用户重定向到同一页面。但是，每当ModelState无效时，我都会得到例外，例如

例外

参数字典包含一个无效类型的参数'referalId'system.int32'for Method'System.web.mvc.m.mvc.madresult referralConfirnation（int32）'中的参数'referalId'。可选参数必须是参考类型，可随机的类型，或称为可选参数。 参数名称：参数

模型：

public class ReferrerInstanceViewModel
    {
        [Key]
        public int Id { get; set; }
        [FileType("pdf|doc|docx|PDF", ErrorMessage = "File type is not valid.")]
        [Required]
        public HttpPostedFileBase ProofDoc { get; set; }
        [Required]
        public int ReferralId { get; set; }
        [Required]
        public int? ReferralStatusId { get; set; }
        public IEnumerable<SelectListItem> ReferralStatuses { get; set; }
    }

控制器动作：

    public ActionResult ReferralConfirmation(int referralId)
    {
        var viewModel = new ReferrerInstanceViewModel
        {
            ReferralId = referralId,
            ReferralStatuses = _context.ReferralStatuses.Select(x => new SelectListItem
            {
                Text = x.ReferralStatusType,
                Value = x.ReferralStatusId.ToString()
            })
        };
        return View(viewModel);
    }
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult ReferralConfirmation(ReferrerInstanceViewModel viewModel)
    {
        if (!ModelState.IsValid)
            return RedirectToAction("ReferralConfirmation", viewModel.ReferralId);
       // Some Logic
        return RedirectToAction("ReferrerCenter");
    }

查看：

@using (Html.BeginForm("ReferralConfirmation", "Referrer", null, FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    @Html.AntiForgeryToken()
    @Html.HiddenFor(m=>m.ReferralId)
    <div class="form-horizontal">
        <h4>ReferrerInstanceViewModel</h4>
        <hr />
        @Html.ValidationSummary(false, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.ReferralStatusId, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownListFor(model => model.ReferralStatusId, Model.ReferralStatuses, "Reject Or Refer", new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.ReferralId, "*", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(model => model.ProofDoc, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.TextBoxFor(m => m.ProofDoc, new { type = "file" })
                @Html.ValidationMessageFor(model => model.ProofDoc, "*", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

注意：

1. 当ModelState无效时，我正在调用RedirectToAction("ReferralConfirmation", I AM PASSING THE REQUIRED ReferralId VALUE HERE)
2. 当模型状态无效时，即使是httpget转介确认行动的断点也不会受到打击。

我无法理解这种行为。我在做什么错。

请注意，ModelState是无效的URL是

https://localhost:44328/Referrer/ReferralConfirmation

Answer 1

用对象调用 RedirectToAction时，您应该通过属性名称与您的转介申请书的参数名称匹配的匿名对象

return RedirectToAction("ReferralConfirmation", 
                                   new { referralId = viewModel.ReferralId } );

这将返回带有位置值的302响应，因为/ReferralConfirmation?referralId=100假设ViewModel中的值。ReferralId是100

同样，当模型状态无效时，进行重定向没有意义。您应该返回相同的视图，以便用户可以修复视图并重新提交。

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult ReferralConfirmation(ReferrerInstanceViewModel viewModel)
{
    if (ModelState.IsValid)
    {
       //to do : Your code before the redirect goes here
        return RedirectToAction("ReferralConfirmation", 
                                         new { referralId = viewModel.ReferralId });
    }
    //model validation failed. Let's return to same view
    return View(viewModel);
}