ASP.Net MVC - 一个未显示的子菜单

Question

我是初学程序员。我试图显示层次结构，但没有显示一个嵌套的子菜单。我想我的逻辑中有一个错误，但无法找到。任何人都想指出在UI中没有显示一个名为 child 4 的子菜单的区域。

以下是代码

public ActionResult Index()
{
    List<MenuItem> mi = new List<MenuItem>
    {
        new MenuItem {Id=1,Name="Parent 1", ParentId=0},
        new MenuItem {Id=2,Name="child 1", ParentId=1},
        new MenuItem {Id=3,Name="child 2", ParentId=1},
        new MenuItem {Id=4,Name="child 3", ParentId=1},
        new MenuItem {Id=5,Name="Parent 2", ParentId=0},
        new MenuItem {Id=6,Name="child 4", ParentId=4}
    };
    ViewBag.menusList = mi;
    return View();
}


public class MenuItem
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int ParentId { get; set; }
}

剃刀代码

@{ var menusList = ViewBag.menusList as List<Scaffolding.Controllers.MenuItem>; }

@if (menusList != null)
{
    <ul id="menu">
        @foreach(var parentMenu in menusList.Where(p => p.ParentId == 0))
        {
        <li>
            <span>@parentMenu.Name</span>
            @if (menusList.Count(p => p.ParentId == parentMenu.Id) > 0)
            {
                <ul id="menu">
                    @foreach(var childMenu in menusList.Where(p => p.ParentId == parentMenu.Id))
                    {
                        <li>
                            <span>@childMenu.Name</span>
                        </li>
                    }
                </ul>
            }
        </li>
        }
    </ul>
}

UI看起来像

提前感谢。

修改

我已经更改了代码，现在收到了名为

的错误

  

CS1502：最佳重载方法匹配   'ASP._Page_Views_Menu_Index_cshtml.ShowTree（System.Collections.Generic.List）'   有一些无效的论点

我的代码仍无效。这是更新的代码

剃刀代码

@{
    var menuList = ViewBag.menusList as List<Scaffolding.Controllers.MenuDTO>;
    ShowTree(menuList);
}


@helper ShowTree(List<Scaffolding.Controllers.MenuDTO> menusList)
{
    if (menusList != null)
    {
        foreach (var item in menusList)
        {
            <li>
                <span>@item.Name</span>
                @if (item.Children.Any())
                {
                    <ul>
                        @ShowTree(item.Children)
                    </ul>
                }
            </li>
        }
    }
}

行动代码

public ActionResult Index()
{
    List<MenuItem> allMenu = new List<MenuItem>
    {
        new MenuItem {Id=1,Name="Parent 1", ParentId=0},
        new MenuItem {Id=2,Name="child 1", ParentId=1},
        new MenuItem {Id=3,Name="child 2", ParentId=1},
        new MenuItem {Id=4,Name="child 3", ParentId=1},
        new MenuItem {Id=5,Name="Parent 2", ParentId=0},
        new MenuItem {Id=6,Name="child 4", ParentId=4}
    };


    List<MenuDTO> mi = allMenu
    .Select(e => new
    {
        Id = e.Id,
        Name = e.Name,
        ParentId = e.ParentId,
        Children = allMenu.Where(x => x.ParentId == e.Id).ToList()
    }).ToList()
    .Select(p => new MenuDTO
    {
        Id = p.Id,
        Name = p.Name,
        ParentId = p.ParentId,
        Children = allMenu.Where(x => x.ParentId == p.Id).ToList()
    }).ToList();

    ViewBag.menusList = mi;

    return View();
}

班级代码

public class MenuItem 
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int ParentId { get; set; }
    public virtual ICollection<MenuItem> Children { get; set; }
}

public class MenuDTO 
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int ParentId { get; set; }
    public virtual ICollection<MenuItem> Children { get; set; }
}

Answer 1

我想发布完整的工作代码。

@helper ShowTree(List<Scaffolding.Controllers.MenuItem> menusList)
{
    <ul>
        @foreach (var item in menusList)
        {
            <li>
                <span>@item.Name</span>
                @if (item.Children!=null && item.Children.Any())
                {
                    @ShowTree(item.Children)
                }
            </li>
        }
    </ul>
}

@{
    var menuList = ViewBag.menusList as List<Scaffolding.Controllers.MenuItem>;
    @ShowTree(menuList);
}

public ActionResult Index()
{

    List<MenuItem> allMenu = new List<MenuItem>
    {
        new MenuItem {Id=1,Name="Parent 1", ParentId=0},
        new MenuItem {Id=2,Name="child 1", ParentId=1},
        new MenuItem {Id=3,Name="child 2", ParentId=1},
        new MenuItem {Id=4,Name="child 3", ParentId=1},
        new MenuItem {Id=5,Name="Parent 2", ParentId=0},
        new MenuItem {Id=6,Name="child 4", ParentId=4}
    };


    List<MenuItem> mi = allMenu
    .Where(e => e.ParentId == 0) /* grab only the root parent nodes */
    .Select(e => new MenuItem
    {
        Id = e.Id,
        Name = e.Name,
        ParentId = e.ParentId,
        Children = allMenu.Where(x => x.ParentId == e.Id).ToList()
    }).ToList();

    ViewBag.menusList = mi;

    return View();
}

public class MenuItem 
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int ParentId { get; set; }
    public virtual List<MenuItem> Children { get; set; }
}