在ASP.NET MVC中的HTML.DropDownList Helper方法中显示分层数据

我在数据库中有一个表，该表本身具有外键.在添加产品产品时，我希望用户能够从DropDownList中选择一个类别.现在，我可以显示如下结果::

I have a table in database that has a foreign key to itself. While adding product products I want the users to be able to select a category from DropDownList. Right now, I am able to show the result like following ::

• 电子
• MP3播放器

• Electronics
• MP3 Players

但是，如果这样显示它们，将是理想的，因为MP3 Player是Electronics的子代:-

But, it would be ideal if they are shown like this, since MP3 Player is a child of Electronics :-

• 电子
  • MP3播放器
  • Electronics
    • MP3 Players

    如何在DropDownList中实现此目标?我当前用于检索和显示的代码分别如下:-

    How can I achieve this in a DropDownList ? My current code for retrieving and displaying is following respectively :-

        public ActionResult Create()
        {
            ViewBag.ParentCategoryID = new SelectList(db.Categories, "CategoryID", "CategoryName");
            return View();
        }
    

    CSHTML

    <div class="editor-field">
            @Html.DropDownList("ParentCategoryID", String.Empty)
            @Html.ValidationMessageFor(model => model.ParentCategoryID)
        </div>