@helper  BuildTreeView(IEnumerable<dynamic> data, int? parentid = 1, int level = 0, string accumulatore = "")
    {
    var nodes = data.Where(n => n.ParentId == parentid).OrderBy(n => n.DisplayOrder);
    var separatore = "";
    if (nodes.Any())
    {
    if (nodes.First().ParentId != null)
    {
    if (level > 0)
    {
    separatore = " >> ";
    }
    }

    if (level == 0){
    @Html.Raw("<select>");
        }
        foreach (var node in nodes)
        {
        var fullText = accumulatore + separatore + node.Text;
        @Html.Raw(string.Format("\r\n<option value=\"{0}\">{1}</option>", node.Text, fullText));
        @BuildTreeView(data, node.Id, level + 1, fullText);
        }
        if (level == 0){
        @Html.Raw("\r\n</select>");
    }
    }
    }