从嵌套对象中获取不同的值列表

Question

我正在将 XML 文件反序列化为对象模型。虽然这不是实际模型，但下面的结构与我的相似。

[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; }

}

我正在尝试获取一个不同的 SelectedCar.Color 值列表，但没有成功。假设我将数据存储在一个名为 autoBody 的变量中，我尝试了以下变体：

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

我显然做错了什么，但不清楚如何实现我想要的。

Answer 1

SelectMany() 方法用于将多个数组（实际上是实现 IEnumerable<T> 的任何东西）投影到单个数组中。

例如，如果您有一个包含 AutoBody 个项目的列表，并且您想要将所有相关联的 Vehicles 累积到一个数组中，您可以这样做：

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

但是，当您在 string 属性上使用 SelectMany（在您的情况下为 Color）时，您基本上是在投影 string 到 IEnumerable<char> 中（因为 String 确实实现 IEnumerable<char> 因为它实际上是一个字符序列）。

尝试使用 Select() 代替：

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

见MSDN

Answer 2

试试这个

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; }

    }
}

从嵌套对象中获取不同的值列表

Get Distinct List of Values from Nested Object

c#

linq

linq-to-objects