在IGrouping中创建IGrouping

Question

我有一个平面ViewModels的List。

var initialList = new List<ViewModel>
{
new ViewModel { OuterCaption = "A outer", InnerCaption = "A inner", Caption = "E", Id = 8},
new ViewModel { OuterCaption = "B outer", InnerCaption = "B inner", Caption = "A", Id = 5},
new ViewModel { OuterCaption = "A outer", InnerCaption = "B inner", Caption = "A", Id = 12},
new ViewModel { OuterCaption = "B outer", InnerCaption = "B inner", Caption = "B", Id = 9},
new ViewModel { OuterCaption = "A outer", InnerCaption = "B inner", Caption = "B", Id = 23},
new ViewModel { OuterCaption = "B outer", InnerCaption = "C inner", Caption = "A", Id = 10},
new ViewModel { OuterCaption = "A outer", InnerCaption = "B inner", Caption = "C", Id = 16},
new ViewModel { OuterCaption = "A outer", InnerCaption = "A inner", Caption = "C", Id = 4},
new ViewModel { OuterCaption = "A outer", InnerCaption = "A inner", Caption = "D", Id = 7},
new ViewModel { OuterCaption = "C outer", InnerCaption = "A inner", Caption = "A", Id = 31},
new ViewModel { OuterCaption = "B outer", InnerCaption = "A inner", Caption = "A", Id = 19},
new ViewModel { OuterCaption = "B outer", InnerCaption = "A inner", Caption = "B", Id = 20},
new ViewModel { OuterCaption = "A outer", InnerCaption = "A inner", Caption = "A", Id = 1},
new ViewModel { OuterCaption = "A outer", InnerCaption = "A inner", Caption = "B", Id = 3}
}.OrderBy(vm => vm.OuterCaption).ThenBy(vm => vm.InnerCaption).ThenBy(vm => vm.Caption);

其中每个ViewModel如下。

class ViewModel
{
public string OuterCaption { get; set; }
public string InnerCaption { get; set; }
public string Caption { get; set; }
public int Id { get; set; }
}

现在我想用OuterCaption对List进行分组，然后用InnerCaption对其进行分组。我可以像这样用OuterCaption对List进行分组。

var list = initialList.GroupBy(vm => vm.OuterCaption).ToList();

并像这样在我的View中使用它，并在View中使用GroupBy。

foreach (var outerGrouping in list)
{
Console.WriteLine(outerGrouping.Key);
Console.WriteLine("~~~~~~~~~~~~~~~~~~");
foreach (var innerGrouping in outerGrouping.GroupBy(vm => vm.InnerCaption))
{
Console.WriteLine(innerGrouping.Key);
foreach (var vm in innerGrouping)
{
Console.WriteLine("Caption: " + vm.Caption + " Id:" + vm.Id);
}
Console.WriteLine("------------------");
}
Console.WriteLine("~~~~~~~~~~~~~~~~~~");
}

但我想在IGrouping中创建一个IGrouping，而不是在View中使用GroupBy(或Linq(。我确实认为我应该为我的View创建类似IReadOnlyList<IGrouping<string, IGrouping<string, ViewModel>>>的东西(可能是错误的(。如何使用initialList实现这一点，以便从View中删除Linq？

以下是示例代码：https://dotnetfiddle.net/hP2kxO

Answer 1

这是有效的。这并不完全是我想要的，但它从我的View中删除了Linq。

var list = initialList
.GroupBy(vm => (vm.OuterCaption, ViewModel: vm))
.GroupBy(group => group.Key.ViewModel.InnerCaption)
.ToList();