Refreshing A Dropdownlist After Elements Have Been Reset

i have an asp.net mvc 2 application, and have some jquery that defines behaviour of two dropdownlists. When one changes, the other is populated with filtered data. After much furor

Solution 1:

Try this:

$(function () {
    $.fn.loadSelect = function (data) {
        returnthis.each(function () {
            this.options.length = 0;
            var select = this;
            $.each(data, function (index, itemData) {
                var option = newOption(itemData.Text, itemData.Value);
                $(select).append(option);
            });
        });
    };
});

Notice that we need to capture this in the outer foreach because in the inner it no longer points to the select element.

Full working example:

Model:

publicclassItem
{
    publicint Value { get; set; }
    publicstring Text { get; set; }
}

publicclassMyViewModel
{
    publicint? SelectedCompanyId { get; set; }
    publicint? SelectedFieldOfficeId { get; set; }
    public IEnumerable<Item> Companies { get; set; }
    public IEnumerable<Item> FieldOffices { get; set; }
}

Controller:

[HandleError]
publicclassHomeController : Controller
{
    public ActionResult Index()
    {
        var model = new MyViewModel
        {
            Companies = Enumerable.Range(1, 5).Select(i => new Item
            { 
                Value = i, 
                Text = "Company " + i 
            }),
            FieldOffices = Enumerable.Empty<Item>()
        };
        return View(model);
    }

    public ActionResult FilterFieldOffices(int companyId)
    {
        return Json(Enumerable.Range(1, 3).Select(i => new Item
        {
            Value = i,
            Text = "Field offfice " + i
        }));
    }
}

View:

<script type="text/javascript" src="<%= Url.Content("~/scripts/jquery-1.4.1.js") %>"></script>
<scripttype="text/javascript">
    $(function () {
        $('#cid').change(function () {
            var coid = $(this).val();
            $.post('<%= Url.Action("FilterFieldOffices") %>', { companyId: coid }, function (data) {
                $('#foid').loadSelect(data);
            });
        });
    });

    $(function () {
        $.fn.loadSelect = function (data) {
            returnthis.each(function () {
                this.options.length = 0;
                var select = this;
                $.each(data, function (index, itemData) {
                    var option = newOption(itemData.Text, itemData.Value);
                    $(select).append(option);
                });
            });
        };
    });

</script>

<% using (Html.BeginForm()) { %>
    <%: Html.DropDownListFor(x => x.SelectedCompanyId, newSelectList(Model.Companies, "Value", "Text"), new { id = "cid" })%>
    <%: Html.DropDownListFor(x => x.SelectedFieldOfficeId, newSelectList(Model.FieldOffices, "Value", "Text"), new { id = "foid" })%>
    <inputtype="submit"value="OK" />
<% } %>