如何使用parentID和ordermenu订购

Question

我有一张菜单，它的特点如下：

tblMenu: ID，标题，ParentID，OrderM

我希望按以下方式选择ParentID和OrderM的菜单和订单：

例：

表中的数据：

ID = 1  Title = menu1 ParentID = 0 OrderM = 1
ID = 2  Title = menu2 ParentID = 0 OrderM = 2
ID = 3  Title = menu3 ParentID = 0 OrderM = 3
ID = 4  Title = submenu2-1 ParentID = 2 OrderM = 1
ID = 5  Title = submenu2-2 ParentID = 2 OrderM = 2
ID = 6  Title = submenu1-2 ParentID = 1 OrderM = 2
ID = 7  Title = submenu1-1 ParentID = 1 OrderM = 1

我希望通过选择LINQ获得以下结果：

menu1
submenu1-1
submenu1-2
menu2
submenu2-1
submenu2-2
menu3

Answer 1

这应该有效(示例)：

var result =
  l.Where(c => c.ParentID == 0)
   .Select(c => new {Menu = c, Sub = l.Where(ci => ci.ParentID == c.ID).OrderBy(s => s.OrderM)})
   .OrderBy(ao => ao.Menu.OrderM)
   .SelectMany(ao => ao.Sub.Count() == 0 ? new List<C> {ao.Menu} : new List<C> {ao.Menu}.Concat(ao.Sub));

Answer 2

如果排序有问题，请尝试使用OrderBy和ThenBy来实现所需的顺序。

例如：

 var items = source.OrderBy(i => i.OrderM).ThenBy(o => o.ParentID);