从MVC 4缺少值中查看控制器列表？

Question

After many years of getting a lot of great advice here, I finally have hit a wall teaching myself MVC4 ASP.net.

I used this post this post to pass a List of Type Class from my controller, to my view, and back to the controller..

public ActionResult SelectProducts()
{
    displayProductsList = db.Products.ToList();
    displayProductsList.ForEach(delegate(Product p)
    {
        //get list of recievables for the product
        GetReceivablesByProductId(p.ProductID).ForEach(delegate(Receivable r)
        {
            //Get count of items in inventory for each recievable                  
            p.CurrentInventory += this.CountItemsByReceivableID(r.RecievableID);
        });                
    });
    return View(FilterProductInventoryList(displayProductsList));
}

And here is my view code..

@model List<CarePac2.Models.Product>

@{
    ViewBag.Title = "SelectProducts";
}

<h2>SelectProducts</h2>
@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true)
    <table>
        @*row values*@
        @for (int i = 0; i < Model.Count; i++)
        {
            <tr>
                <td>@Html.DisplayFor(m => m[i].Brand)</td>
                <td>@Html.DisplayFor(m => m[i].ProductName)</td>
                <td>@Html.DisplayFor(m => m[i].UnitType)</td>
                <td>@Html.DisplayFor(m => m[i].SalePrice)</td>
                <td>@Html.DisplayFor(m => m[i].CurrentInventory)</td>
                <td>                  
                    @Html.EditorFor(m => m[i].OrderQuantity)
                    @Html.ValidationMessageFor(m => m[i].OrderQuantity)
                </td>
                <td></td>
            </tr>
        }
    </table>
    <p>
        <input type="submit" value="Save" />
        @*<input type="submit" value="Cancel" />*@
    </p>
}

@section Scripts {
@Scripts.Render("~/bundles/jqueryval")

Here the view show it has values for the List that was passed from controller to view..

Visually the view displays the data correctly (apparently i can't post an image of it until i have 10 reputation to post images)

when i hit submit and return to the controller:

 [HttpPost]
 [ValidateAntiForgeryToken]
 public ActionResult SelectProducts(List<Product> selectedProducts)
 {
     if (ModelState.IsValid)
     {
     }
 }

The variable selectedProducts Is NOT NULL. The list has 3 Product items in it, however, as you can see in the image below in the debugger, even though i have 3 product items, none of the values exist from when the List of Product was originally passed to the view...

for example (since i can't post images yet):

selectedProducts[0].ProductID=0
selectedProducts[0].ProductName=null
selectedProducts[1].ProductID=0
selectedProducts[1].ProductName=null

Answer 1

You need to use @Html.HiddenFor() :

@Html.HiddenFor(m => m[i].ProductID)
@Html.HiddenFor(m => m[i].ProductName)

This will send the data back to the controller. This creates an <input type="hidden"> that will be part of the form POST.