如何使用JSon填充@html.dropdownlist mvc帮助器

public ActionResult GetDropdownData()
{
    var data = new List<SelectListItem>
    {
        new SelectListItem { Value = "1", Text = "Option 1" },
        new SelectListItem { Value = "2", Text = "Option 2" },
        new SelectListItem { Value = "3", Text = "Option 3" }
    };

    return Json(data, JsonRequestBehavior.AllowGet);
}

<script>
    $(document).ready(function() {
        $.ajax({
            url: '/ControllerName/GetDropdownData',
            type: 'GET',
            dataType: 'json',
            success: function(data) {
                var dropdown = $('#DropdownId');
                dropdown.empty();
                $.each(data, function(index, item) {
                    dropdown.append($('<option></option>').val(item.Value).text(item.Text));
                });
            }
        });
    });
</script>

@Html.DropDownList("DropdownId", new SelectList(Enumerable.Empty<SelectListItem>(), "Value", "Text"), "Select an option")