ViewModel is empty MVC2

Question

Hello all,

When I press the submit button and access the Controller my ViewModel is empty. I don't know why this is happening, I have similar code to this on the other views and they do pass through data.

Controller

        public ActionResult DeleteCategory(int id)
        {
            var data = _service.GetIndividualCategory(id);
            if (data == null) return View("NotFound");

            // If attached to traders send to other view
            var traders = _service.GetTradersAttachedToCategory(id);
            if (!traders.Any())
            {
                var category = new DeleteCategoryViewModel
                {
                    Description = data.Description,
                    Id = data.Id
                };

                return View(category);
            }

            var trader = new DisplayTradersAttachedToCategoryViewModel
            {
                Description = data.Description,
                Id = data.Id,
                BusinessName = traders.Select(x => new BusinessNameViewModel { BusinessName = x.BusinessName, Id = x.Id }),
                Categories = _service.GetCategories(id).Select(x => new SelectListItem {Text = x.Description, Value = x.Id.ToString()})
            };

            return View("DeleteCategoryAttachedToTraders", trader);
        }

Accessed when 'Submit' button hit

       [HttpPost]
        public ActionResult DeleteCategoryFromTradersAttachNewCategory(DisplayTradersAttachedToCategoryViewModel displayTradersAttachedToCategoryViewModel)
        {
            if (displayTradersAttachedToCategoryViewModel.Button == "Back to List") return RedirectToAction("ViewCategories");

            //Update traders with new category
            //delete category

            //if (_service.DeleteCategory((int)deleteCategoryViewModel.Id))
            //{
            //    return RedirectToAction("ViewCategories");
            //}

            return View("DeleteCategoryAttachedToTraders", displayTradersAttachedToCategoryViewModel);
        }

DeleteCategoryAttachedToTraders.aspx

<%@ Page Title="Delete Category - Traders Attached to Category" Language="C#" MasterPageFile="~/Views/Shared/Master.Master" Inherits="System.Web.Mvc.ViewPage<Internal.ViewModels.Controller.DisplayTradersAttachedToCategoryViewModel>" %>

<asp:Content ID="pageTitle" ContentPlaceHolderID="PageTitle" runat="server">
  Delete Category - Traders Attached to Category
</asp:Content>

<asp:Content ID="htmlHead" ContentPlaceHolderID="HtmlHead" runat="server">
  <link href="<%=ResolveUrl("~/Assets/Styles/CSS.css")%>" rel="Stylesheet" type="text/css" />
</asp:Content>

<asp:Content ID="bodyContent" ContentPlaceHolderID="BodyContent" runat="server">
  <div class="center"><%
    using (Html.BeginForm("DeleteCategoryFromTradersAttachNewCategory", "Controller",FormMethod.Post))
    {%>    
      <h2>Delete Category - Traders Attached to Category</h2>
      <div class="magiPadBig"></div>

      <div class="magiPadBig"></div>      
      <%=Html.DisplayFor(x => x.BusinessName)%>

      <div class="magiPadBig"></div>   
      <h3>New Category</h3>

      <div class="magiPadBig"></div>    
      <%=Html.DropDownList("Categories")%>

      <div class="magiPadBig">  
        <input type="submit" name="Button" value="Back to List" />
        <input type="submit" name="Button" value="Submit" />
      </div><%
    }%>
  </div>
</asp:Content>  

DisplayTradersAttachedToCategoryViewModel

public class DisplayTradersAttachedToCategoryViewModel
{
    public int Id { get; set; }
    public string Description { get; set; }

    [UIHint("BusinessNameDisplayTemplate")]
    public IEnumerable<BusinessNameViewModel> BusinessName { get; set; }

    public IEnumerable<SelectListItem> Categories { get; set; }

    public int Category { get; set; }

    public string Button { get; set; } 
}

Thanks in advance for any help.

Clare

Answer 1

The problem I can see (and I fully expect others to correct me here) is the following: (edited for clarity)

1. Id won't be set because you are posting to a different form, and there is no hidden field for the ID, so it won't be set.
2. Description won't be set, as there is nothing for it to be set from.
3. Categories won't be set, because the Ienumerable is populated only in your get, and not your post (which is fair enough, as you aren't posting the whole list).
4. Category isn't populated because you've named the drop down list "Categories", and so it won't match the name "Category" in the viewmodel.

Try

<%=Html.DropDownList("Category", Model.Categories)%>