Get ViewData IList back on postback in ASP.NET MVC

I have the following in my view:

<%using (Html.BeginForm()) {%>
<% foreach (var item in Model.Cart) { %>
    <div>
        <%= Html.TextBox("Cart.Quantity", item.Quantity, new { maxlength = "2" })%>
        <%= Html.Hidden("Cart.ItemID", item.ItemID)%>
    </div>
<% } %>
<input name="update" type="image" src="image.gif" />

I then have this code in my controller:

    public ActionResult Index()
    {
      开发者_运维技巧  CartViewData cartViewData = new CartViewData();
        IList<Item> items = ItemManager.GetItems();

        cartViewData.Cart = items;
        return View("Index", cartViewData);
    }

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult Index(CartViewData cartViewData)
    {
        // cartviewData is null
    }

Is there a way to grab the List on the postback to see if the values in the textboxes have changed?

Thanks

Below is a simplified example since it was requested:

<% for (int i = 0; i < Model.Cart.Count; i++ ) { %>
    <a href="javascript:void(0);" onclick="removeItem(<%= Model.Cart[i].ShoppingCartItemID %>);">Remove</a>
<% } %>

Hope this helps.

This simplest way is to do this - name each cart item control with this format:

<input type="text" name="Items[0].Quantity" />

Where the 0 corresponds to the index of the item in the items collection. Next, move the items collection to a property on the cart, so that you model looks something like this:

class CartViewData 
{
    public CartViewData()
    {
        this.Items = new List<Item>();
    }

    public IList<Item> Items { get; private set; }

    class Item
    {
       public int Quantity { get; set; }
    }
}

Then the DefaultModelBinder will bind the values to the model.