Why won't my Model accept what I'm selecting from the DropDownList?

Question

I edit the Dinner (from the NerdDinner tutorial) and save it, but the Country isn't persisted. Here's my code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace NerdDinner.Models
{
    public class DinnerFormViewModel
    {
        private static string[] _countries = new[]{
            "USA",
            "Bolivia",
            "Canada"
        };

        public Dinner Dinner { get; private set; }
        public SelectList Countries { get; private set; }

        public DinnerFormViewModel(Dinner dinner)
        {
            Dinner = dinner;
            Countries = new SelectList(_countries, dinner.Country);
        }
    }
}

Then in my controller I use it like so:

[HttpGet]
public ActionResult Edit(int id)
{
    Dinner dinner = dinnerRepository.GetDinner(id);            

    return View(new DinnerFormViewModel(dinner));
}

[HttpPost]
public ActionResult Edit(int id, FormCollection formValues)
{
    Dinner dinner = dinnerRepository.GetDinner(id);

    if (TryUpdateModel(dinner))
    {
        dinnerRepository.Save();
        return RedirectToAction("Details", new { id = dinner.DinnerID });
    }

    return View(new DinnerFormViewModel(dinner));
}

Then, here is the View:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<NerdDinner.Models.DinnerFormViewModel>" %>

<div class="editor-label">
    <%: Html.LabelFor(model => model.Dinner.Country) %>
</div>
<div class="editor-field">
    <%: Html.DropDownListFor(model => model.Dinner.Country, Model.Countries) %>                
    <%: Html.ValidationMessageFor(model => model.Dinner.Country) %>
</div>

When trying to edit an existing dinner and change the Country, it doesn't persist the change. Thanks!

Answer 1

So are you saying that when you call TryUpdateModel(dinner), the dinner properties are being updated with what's in the form?

If that's the case, because Country is a child of the model and you are calling the html helpings like so, <%: Html.DropDownListFor(model => model.Dinner.Country, Model.Countries) %>, I'm thinking that the inputs will have a prefix of Country.

Try changing your TryUpdateModel(dinner) to TryUpdateModel(dinner, "Dinner").

HTHs,
Charles