從嵌套對象中獲取不同的值列表

Question

我將XML文件反序列化為對象模型。 雖然這不是實際的模型，但下面的結構與我的相似。

[Serializable()]
[System.Xml.Serialization.XmlRoot("AutoEnvelope")]
public class AutoBody
{
    [XmlArray("AutoBody")]
    [XmlArrayItem("Vehicles", typeof(Vehicles))]
    public Vehicles[] Vehicles { get; set; }

}

[Serializable()]
public class Vehicles
{
    [XmlElement("SelectedCar", typeof(SelectedCar))]
    public SelectedCar SelectedCar { get; set; }

    [XmlElement("OfferedVehicles", typeof(OfferedVehicles))]
    public OfferedVehicles OfferedVehicles { get; set; }

}

[Serializable()]
public class SelectedCar
{
    [System.Xml.Serialization.XmlElement("Model")]
    public string Model { get; set; }

    [System.Xml.Serialization.XmlElement("NumTires")]
    public int NumTires { get; set; }

    [System.Xml.Serialization.XmlElement("Color")]
    public string Color { get; set; }

}

我試圖獲得一個獨特的SelectedCar.Color值列表，並且不成功。 讓我們假設我將數據存儲在一個名為autoBody的變量中，我嘗試過以下變體：

List<char> uniqueColors = autoBody.SelectMany(auto => auto.SelectedCar.Color).Distinct().ToList();

我顯然做錯了什么，但我不清楚如何實現我正在尋找的東西。

Answer 1

SelectMany()方法用於將多個數組（實際上是實現IEnumerable<T>任何數組SelectMany()投影到單個數組中。

例如，如果您有一個AutoBody項目列表，並且您想將所有關聯的Vehicles累積到一個陣列中，您可以：

IEnumerable<Vehicles> vehicles = autoBodies.SelectMany(x => x.Vehicles);

但是，當你使用SelectMany在string屬性（ Color在你的情況下），你基本上投射string入IEnumerable<char> （因為String 確實實現IEnumerable<char> ，因為它實際上是一個字符序列）。

嘗試使用Select()代替：

List<string> uniqueColors = autoBody.Select(auto => auto.SelectedCar.Color)
                                    .Distinct()
                                    .ToList()

請參閱MSDN

Answer 2

試試這個

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

namespace ConsoleApplication70
{
    class Program
    {
        static void Main(string[] args)
        {
            AutoBody bodies = new AutoBody()
            {
               vehicles = new List<Vehicles>()
                {
                    new Vehicles() {
                        SelectedCar = new SelectedCar() { Model = "Ford", NumTires = 1, Color = "red"}
                    },
                    new Vehicles() {
                        SelectedCar = new SelectedCar() { Model = "Chevy", NumTires = 2, Color = "blue"}
                    },
                    new Vehicles() {
                        SelectedCar = new SelectedCar() { Model = "Jeep", NumTires = 3, Color = "green"}
                    },
                    new Vehicles() {
                        SelectedCar = new SelectedCar() { Model = "Merecedes", NumTires = 4, Color = "red"}
                    },
                }
            };
            List<string> colors = bodies.vehicles.Select(x => x.SelectedCar).Select(y => y.Color).Distinct().ToList();

        }
    }
    [Serializable()]
    [System.Xml.Serialization.XmlRoot("AutoEnvelope")]
    public class AutoBody
    {
        [XmlArray("AutoBody")]
        [XmlArrayItem("Vehicles", typeof(Vehicles))]
        public List<Vehicles> vehicles { get; set; }

    }

    [Serializable()]
    public class Vehicles
    {
        [XmlElement("SelectedCar", typeof(SelectedCar))]
        public SelectedCar SelectedCar { get; set; }

        //[XmlElement("OfferedVehicles", typeof(OfferedVehicles))]
        //public OfferedVehicles OfferedVehicles { get; set; }

    }

    [Serializable()]
    public class SelectedCar
    {
        [System.Xml.Serialization.XmlElement("Model")]
        public string Model { get; set; }

        [System.Xml.Serialization.XmlElement("NumTires")]
        public int NumTires { get; set; }

        [System.Xml.Serialization.XmlElement("Color")]
        public string Color { get; set; }

    }
}