@model List<CourseCategory>
@{
    if (Model != null && Model.Count > 0)
    {
        <ul @Html.Raw(ViewData.ContainsKey("IsTopLevel") ? "class='filetree treeview'" : "")>
            @{
                ViewData.Remove("IsTopLevel");
            }
            @foreach (var item in Model)
            {
                <li>
                    <a href="@Url.Action("Index","Course",new { categoryId=item.Id})"><span class="folder">@item.Name</span></a>
                    @await Html.PartialAsync("_Menu", item.Children, this.ViewData)
                </li>
            }
        </ul>
    }
}