无效的模型状态：当我有下拉列表时如何返回视图？

Question

我有 40 多个领域的大视野。其中一些字段是下拉列表，我用选择列表项列表填充。

我正在使用我的视图模型上的注释，以使其中一些成为必需的。

现在我想做ModelState.IsValid检查，如果有错误返回原来的视图。

问题是，如果我只是创建一个return View(model)，我所有的下拉列表都会使网站崩溃，因为需要再次填充它们才能加载页面。

所以我的问题是：当模型状态无效时我如何处理返回。

我的控制器：

    public ActionResult CreateSelling(SellingAdViewModel model)
    {
        if (ModelState.IsValid)
        {
            SellingAdvert sellingAdvert = setSellingAd(model);

            var stored_advert = sellingAdvertService.Create(sellingAdvert);



            if (User != null && User.Identity.IsAuthenticated)
            {
                if (model.AcceptPartner)
                {
                    notifyPartner(stored_advert);
                }

                return RedirectToAction("Upgrade", "Ads", new { AdvertID = stored_advert.Id });
            }
            else
            {
                return RedirectToAction("ActivateAnonymous", "Ads", new { AdvertID = stored_advert.Id, anonymousId = model.UserId, AdvertType = "selling" });
            }
        }

        return View(model);
    }

我的视图模型（我有一个 SellingAdViewModel 派生自这个模型并添加了更多属性）：

public class BasicAdViewModel
{
    public int SectorId { get; set; }
    public Guid UserId { get; set; }
    public bool IsAnonymousUser { get; set; }
    public int AdvertId { get; set; }

    [DisplayName("Titel:")]
    [Required(ErrorMessage = "Titel skal udfyldes")]

    public string Headline { get; set; }

    [DisplayName("Beskrivelse:")]
    [StringLength(50, ErrorMessage = "Beskrivelsen minimum fylde 50 karakterer")]
    public string Description { get; set; }

    [DisplayName("Søgeord:")]
    public string SearchWords { get; set; }


    [DisplayName("Undertitel:")]
    public string Subtitle { get; set; }

    [DisplayName("Type af drift")]
    public List<SelectListItem> OperationTypes { get; set; }

    [Required]
    public int SelectedOperationTypeId { get; set; }


    [Required]
    public int SelectedSectorId { get; set; }
    public IEnumerable<GroupedSelectListItem> Sectors { get; set; }
}

首先设置我的下拉列表：

我的模型有 List<SelectListItem> 属性，我通过几个辅助方法来填充它们：

  SellingAdViewModel model = new SellingAdViewModel()
            {
                BusinessEntityTypes = ModelListHelpers.GetBusinessEntityTypes(),
                FoundedYears = ModelListHelpers.GetFoundedYears(null),
                ReasonForSale = ModelListHelpers.GetReasonForSale(),
                RevenuePrediction = ModelListHelpers.GetRevenuePrediction(),
                RevenueStatus = ModelListHelpers.GetRevenueStatus(),
                OperationTypes = ModelListHelpers.GetOperationTypes(),
                Region = ModelListHelpers.GetRegions(),
                Turnover = ModelListHelpers.Turnovers(),
                OperatingIn = ModelListHelpers.OperatingIn(),
                AmountOfEmployees = ModelListHelpers.GetAmountOfEmployees()
            };

Answer 1

我建议你这个解决方案在你的 GET 操作期间将你的模型放在TempData 如果模型状态无效，你可以像这样进行分配

public ActionResult CreateSelling(SellingAdViewModel model)
{
    if (ModelState.IsValid)
    {
        SellingAdvert sellingAdvert = setSellingAd(model);

        var stored_advert = sellingAdvertService.Create(sellingAdvert);



        if (User != null && User.Identity.IsAuthenticated)
        {
            if (model.AcceptPartner)
            {
                notifyPartner(stored_advert);
            }

            return RedirectToAction("Upgrade", "Ads", new { AdvertID = stored_advert.Id });
        }
        else
        {
            return RedirectToAction("ActivateAnonymous", "Ads", new { AdvertID = stored_advert.Id, anonymousId = model.UserId, AdvertType = "selling" });
        }
    }

    model.YourList = TempData.Peek("YourList");
    return View(model);
}