LINQ組列表 <object> 在baseclass屬性上

Question

我得到一個列表，在其中放置了超類的子類實例。

我班的代碼：

public abstract class Vehicle : IComparable< Vehicle >, IComparable 
{
    public string Manufacture{get;set}
    public Int16 VehicleID{get;set}
    public DateTime ProductionDate{get;set}

    public Vehicle(Int16 _ Vehicle ID,DateTime _ProductionDate)
    {
        this.AccidentID = _ AccidentID;
        this.ProductionDate = _ProductionDate;
    }

    int IComparable.CompareTo(object other) 
    {
        return CompareTo((Vehicle)other);
    }
    public int CompareTo(Vehicle other)
    {
        return this.ProductionDate.CompareTo(other.ProductionDate);
    }

    public Vehicle()
    {}
}

public class Car : Vehicle
{
    public Car ()
    {
    }

    public Car (Int16 _VehicleID,DateTime _ProductionDate, Int16 _CarAttribute1, Int16 _CarAttribute2):base(_Vehicle ID,_ProductionDate)
    {
        this.AccidentID = _ AccidentID;
        this.ProductionDate = _ProductionDate;
        this.CarAttribute1 = _CarAttribute1
        this.CarAttribute2 = _CarAttribute2
    }

    public Int16 CarAttribute1{ get; set;}
    public Int16 CarAttribute2{ get; set;}
}

public class MotorCycle : Vehicle
{
    public MotorCycle ()
    {
    }

    public MotorCycle (Int16 _VehicleID,DateTime _ProductionDate, Int16 _MotorCycleAttribute1, Int16 _MotorCycleAttribute2):base(_Vehicle ID,_ProductionDate)
    {
        this.AccidentID = _ AccidentID;
        this.ProductionDate = _ProductionDate;
        this.MotorCycleAttribute1 = _MotorCycleAttribute1
        this.MotorCycleAttribute2 = _MotorCycleAttribute2
    }

    public Int16 MotorCycleAttribute1{ get; set;}
    public Int16 MotorCycleAttribute2{ get; set;}
}

我希望能夠基於我的基類（即制造）中的屬性對這些實例進行分組。

public class Grouping<K, T> : ObservableCollection<T>
{
    public K Key { get; private set; }

    public Grouping(K key, IEnumerable<T> items)
    {
        Key = key;
        foreach (var item in items)
            this.Items.Add(item);
    }
}

• 詳情請參見： http ： //motzcod.es/post/94643411707/enhancing-xamarin-forms-listview-with-grouping-headers#sthash.kWyEfaqU.dpuf

就像是

var sorted = item in allVehicles //including cars and motorcycles
    orderby item.Manufacture
    group item by item.Manufacture into vehicleGroup
    select new Grouping<string, object>(vehicleGroup.Key, vehicleGroup);

任何建議表示贊賞:)

Answer 1

你對什么感興趣

1.從一種類型中獲得全部

您只是對獲得汽車感興趣嗎？ 然后，在以下條件的開頭添加到linq語句中：

.OfType<Car>()...

（感謝Stephen Kennedy，它比“ Where（one => one is Car）.Cast（）”更簡單）

2.獲取分組的類型

還是要對所有類型進行分組？ 然后使用

var list = allVehicles.GroupBy(t => t.GetType());

要么

ILookup<Type, Vehicle> group = allVehicles.ToLookup(x => x.GetType());