POST

Question

尽管我在其他问题中找到了所有建议，this article POST后，传递给视图的 List vsValues 始终为空。

查看

@model OTS.ParcelOrder

@{
    ViewBag.Title = "Create";
    Layout = "~/Views/Shared/_Layout.cshtml";
}


<h2>Create</h2>

@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()
    
    <div class="form-horizontal">
        <h4>ParcelOrder</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.otsID, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.otsID, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.otsID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.parcelID, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.parcelID, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.parcelID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.recipientCountry, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.recipientCountry, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.recipientCountry, "", new { @class = "text-danger" })
            </div>
        </div>


        @for (int i = 0; i < Model.vsValues.Count; i++)
        {
            @Html.Label(Model.ParcelOrder_VSFields.ElementAt(i).VendorSpecifiedInfoField.fieldName, 
           htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.vsValues[i], new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.vsValues[i], "", new { @class = "text-danger" })
            </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>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

控制器

        // GET: ParcelOrders/Create
        public ActionResult Create(int vendorId = 1)
        {
            ParcelOrder order = new ParcelOrder(vendorId);
            return View(order);
        }

        // POST: ParcelOrders/Create
        // Aktivieren Sie zum Schutz vor übermäßigem Senden von Angriffen die spezifischen Eigenschaften, mit denen eine Bindung erfolgen soll. Weitere Informationen 
        // finden Sie unter http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken] 
        public ActionResult Create(ParcelOrder parcelOrder)
        {
            parcelOrder.customerID = User.Identity.GetUserId();
            if (ModelState.IsValid)
            {
                db.ParcelOrder.Add(parcelOrder);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(parcelOrder);
        }

public partial class ParcelOrder
{
    private Entities db = new Entities();
    public List<string> vsValues = new List<string>();

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public ParcelOrder()
    {
        this.ParcelOrder_VSFields = new List<ParcelOrder_VSFields>();
    }


    public ParcelOrder(int vendorId)
    {
        this.ParcelOrder_VSFields = new List<ParcelOrder_VSFields>();

        var vendorQuery = from vsif in db.VendorSpecifiedInfoField
                          where vsif.vendorID == vendorId
                          select vsif;

        foreach (var vsif in vendorQuery)
        {
            vsValues.Add("");
            this.ParcelOrder_VSFields.Add(new OTS.ParcelOrder_VSFields
            {
                vsFieldID = vsif.id,
                VendorSpecifiedInfoField = vsif,
                value = ""
            });
        }
    }

    public string otsID { get; set; }
    public string parcelID { get; set; }
    public string customerID { get; set; }
    public string recipientCountry { get; set; }

    public virtual AspNetUsers AspNetUsers { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<ParcelOrder_VSFields> ParcelOrder_VSFields { get; set; }
}

}

注意 这些值应该在列表vsValues 中进行POST，稍后将在控制器内设置为 ParcelOrder_VSFields 的属性，以避免POST冗余信息。

Answer 1

这是因为你没有在任何地方发布任何内容

data Delayed a = Some a | None deriving (Typeable, Show)

应该像：

test0 :: Typeable a => Delayed a -> String
test0 (Some x) = maybe "not a String" id $ cast x
test0 None     = "None"

test0' =
  let c = castToDelayed test0 in
   [ c (toDyn (None :: Delayed Int))
   , c (toDyn (Some 'a'))
   , c (toDyn (Some "a")) ]

<强>更新

之后。您的模型对我来说是错误的，如果您想将值传递给列表，我建议您具有相同类型的列表属性[此属性需要在您的模型@using (Html.BeginForm()) 中而不是虚拟]。然后在类的无参数构造函数中执行foreach。在您看到问题的每一步中跟踪它。