Challenges with selecting values in ListBoxFor

Here's an example illustrating the strongly typed version:

Model:

public class MyViewModel
{
    public int[] SelectedItemIds { get; set; }
    public MultiSelectList Items { get; set; }
}

Controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        // Preselect items with id 1 and 3
        var selectedItemIds = new[] { 1, 3 };

        var model = new MyViewModel
        {
            Items = new MultiSelectList(
                new[] 
                {
                    // TODO: Fetch from your repository
                    new { Id = 1, Name = "item 1" },
                    new { Id = 2, Name = "item 2" },
                    new { Id = 3, Name = "item 3" },
                }, 
                "Id", 
                "Name", 
                selectedItemIds
            )
        };

        return View(model);
    }
}

View:

<%: Html.ListBoxFor(x => x.SelectedItemIds, Model.Items) %>

I don't know if this behaviour has changed in the RTM of MVC3 that I'm using, but it seems that selection and binding now works out of the box. The only catch is that the model should contain a property with the IDs, like that :

public class MyViewModel {
    public int[] ItemIDs { get; set; }
}

Then the following in the view would work fine, both pre-selecting the correct values and binding correctly during post:

@Html.ListBoxFor(model => model.ItemIDs, (IEnumerable<SelectListItem>)(new[] { 
                                new SelectListItem() { Value = "1", Text = "1" }, 
                                new SelectListItem() { Value = "2", Text = "2" } 
                             }))

I have found better workaround. Usual way to preselect select list:

@Html.ListBoxFor(
    model => model.Roles, 
    new MultiSelectList(db.Roles, "Id", "Name")
)
@Html.ValidationMessageFor(model => model.Roles)

Doesn't work.., never ever any option is selected, until:

public ActionResult Edit(int id)
{
    var user = db.Users.Find(id);
    // this is workaround for http://aspnet.codeplex.com/workitem/4932?ProjectName=aspnet
    ViewData["Roles"] = user.Roles.Select(r => r.Id);
    return View(user);
}

Selected Roles has to be stored in ViewData, to workaround nasty bug.

Challenges with selecting values in ListBoxFor

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