Question

How can I get the results from a JQUery Multi-select dropdownlist as called per an mvc3/razor?

http://abeautifulsite.net/blog/2008/04/jquery-multiselect/

Answer 1

The multiselect plugin uses the [] notation to send the selected values to the server. As always we start by writing a view model:

public class MyViewModel
{
    public IEnumerable<string> SelectedValues { get; set; }

    public IEnumerable<SelectListItem> Items
    {
        get
        {
            return new[]
            {
                new SelectListItem { Value = "1", Text = "item 1" },
                new SelectListItem { Value = "2", Text = "item 2" },
                new SelectListItem { Value = "3", Text = "item 3" },
            };
        }
    }
}

then a controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View(new MyViewModel());
    }

    [HttpPost]
    public ActionResult Index(MyViewModel model)
    {
        return View(model);
    }
}

a corresponding view:

@model MyViewModel

<script src="@Url.Content("~/Scripts/jquery.multiSelect.js")" type="text/javascript"></script>
<script type="text/javascript">
    $(function () {
        $("#SelectedValues").multiSelect();
    });
</script>

@using (Html.BeginForm())
{
    @Html.ListBoxFor(x => x.SelectedValues, Model.Items)
    <button type="submit">OK</button>
}

and finally a model binder associated with the IEnumerable<string> type and which will work with the [] notation used by the plugin:

public class MultiSelectModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var model = (MyViewModel)base.BindModel(controllerContext, bindingContext);
        var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName + "[]");
        if (value != null)
        {
            return value.RawValue;
        }
        return model;
    }
}

The last part is to register the model binder in Application_Start:

ModelBinders.Binders.Add(typeof(IEnumerable<string>), new MultiSelectModelBinder());