MVC 5 Multiselect List Values Not Binding to Model On Post

Question

I have a view with several multiselect lists which are declared like this

<div class="col-md-6">
    @Html.LabelFor(model => model.Counties, htmlAttributes: new { @class = "control-label" })
    @Html.ListBoxFor(model => model.Counties, new MultiSelectList(ViewBag.CountyList, "Value", "Text"), htmlAttributes: new { @class = "form-control", size = 8, tabindex = 26 })
    @Html.ValidationMessageFor(model => model.Counties, "", new { @class = "text-danger" })
    <span class="small">Ctrl + click to select multiple items</span>
</div>

My view model contains a declaration like this:

 public virtual List<long> Counties { get; protected set; }

My action looks like this:

    [HttpPost]
    public ActionResult Edit(TScholarshipView model, FormCollection form)
    {
        if (ModelState.IsValid)
        {
            TScholarship scholarship = Repo.GetScholarship(model.Id);
            scholarship = Mapper.Map<TScholarshipView, TScholarship>(model, scholarship);
            Repo.SaveOrUpdate(scholarship, HttpContext.User.Identity.Name);

            return RedirectToAction("Edit", "AdminScholarship", new { id = model.Id });
        }

        return View("Scholarship", model);
    }

On submit I can look at the post data sent by the browser and it is sending the appropriate data to the server

...&Counties=16&Counties=34&...

When the action begins to execute the value of Counties in the model is null. However I can look at the FormCollection values and the value of form["Counties"] is "16,34". Any ideas why the binding is not occurring?

Answer 1

I noticed this right after I posted the question. The problem was having the setter protected. This prevented the binder from setting the value of the list.