Linq:从扁平化列表重建层次结构数据

问题描述

免责声明::自两天以来，我一直在与这个问题作斗争(我在SO上读过很多类似的问题).通过Linq并寻求帮助.

Disclaimer: I've been fighting against this problem since 2 days (I've read a lot of similar questions on SO).. so be patient, I'm missing something about the Group By with Linq and asking for help.

我有一个Macrotab的列表.每个Macrotab对象都包含一个Tab列表.每个Tab对象都在内部，而Slot在里面.

I have a list of Macrotab. Each Macrotab object contains a list of Tab.Each Tab object inside with Slot inside.

List<MacroTab> hierarchaldata = CreateHierarchaldata();

*为了使问题易于阅读，我将填充一组示例数据的CreateHierarchaldata移到了.NetFiddle中: https://dotnetfiddle.net/8mF1qI

*For keeping the question easy to read I've moved the CreateHierarchaldata, which populates a set of sample data, to .NetFiddle: https://dotnetfiddle.net/8mF1qI

以下几行使用Linq 展平此结构:

The following lines flattens this structure using Linq:

var flattenedList = (from macroTab in hierarchaldata
            from tab in macroTab.Tabs
            from slot in tab.Slots
            select new {macroTab.IDMacroTab, tab.IDTab, slot.IDSlot}).ToList();

将数据聚合回层次结构

我尝试使用Linq Group By回到原始列表.这是我的目标:汇总MacroTab，Tab和Slot的ID的数据并重新创建原始列表，但是它没有按预期工作**:

Aggregate the data back to hierarchy

I've tried to get back to the original list using the the Linq Group By. This was my objective: to Aggregate the data for the Id of the MacroTab, Tabs and Slots and recreate the original list, but it doesn't work as expected**:

var antiflatten = from macrotab in flattenedList
            group macrotab by new {macrotab.IDMacroTab}
            into macrotabs
            let macrotabFirst = macrotabs.First()
            select new MacroTab
            {
                IDMacroTab = macrotabFirst.IDMacroTab,
                Tabs = (from macrotab in macrotabs
                    group macrotabs by new {macrotab.IDTab}
                    into tabs
                    let tabFirst = tabs.First()
                    select new Tab(){ HelperClass = tabFirst}).ToList()
            };

**属性HelperClass仅用于调试目的，希望它不会引起混淆，我将其留给解释了Visual Studio调试器的屏幕截图

**The property HelperClass is just for debugging purpose, I hope it's not confusing, I've left it to explain the Visual Studio debugger's screenshot

在Fiddler上试用

推荐答案

    var macroTabs = flattenedList
        .GroupBy(x => x.IDMacroTab)
        .Select((x) => new MacroTab
        {
            IDMacroTab = x.Key,
            Tabs = x.GroupBy(t => t.IDTab)
                    .Select(tx => new Tab {
                        IDTab = tx.Key,
                        Slots = tx.Select(s => new Slot {
                           IDSlot = s.IDSlot
                     }).ToList()
            }).ToList()
        }).ToList();

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