将范围添加到同一命令/行中的新对象列表答案

【问题标题】：Add range to a new list of object within the same command / line将范围添加到同一命令/行中的新对象列表
【发布时间】：2019-02-22 01:43:24
【问题描述】：

我正在尝试将一系列对象添加到新列表中，但收到以下消息：

无法将类型“void”隐式转换为“System.Collections.Generic.List”

这是我正在尝试的：

Detalhes = new List<DetalhesExcel>() {
    new DetalhesExcel()
    {
        NumColunaInicial = 23,
        Coluna1 = "Representante",
        Coluna2 = "ValorRepasse",
        Coluna3 = "KmRepasse"
    }
}.AddRange(ocorrencias.Where(x => x.Conclusao != "PRÓPRIO")
    .GroupBy(x => x.Representante)
    .Select(x => new DetalhesExcel
    {
        NumColunaInicial = 23,
        Coluna1 = x.First().Representante,
        Coluna2 = x.Sum(y => y.ValorRepasse).ToString(),
        Coluna3 = x.Sum(y => y.KmRepasse).ToString()
    }).ToList())

我需要做什么？

DetalhesExcel 类：

public class DetalhesExcel
{
    public int NumColunaInicial { get; set; }
    public string Coluna1 { get; set; }
    public string Coluna2 { get; set; }
    public string Coluna3 { get; set; }
    public string Coluna4 { get; set; }
    public string Coluna5 { get; set; }
}

【问题讨论】：

请把你的 DetalhesExcel 类放在代码上
@JoãoPauloAmorim DetalhesExcel 类结构与它无关。
@Sumitraj 我只是想在这里重新创建它，抱歉
@joão-paulo-amorim 好的，我已经在课堂上更新了它。
.AddRange 需要单独调用，因为它返回void。改用Concat

标签： c# list linq

【解决方案1】：

我想你想要的是这样的

    class Program
{
    static void Main(string[] args)
    {
        List<Ocorrencia> ocorrencias = new List<Ocorrencia>() {
            new Ocorrencia() {
                Conclusao = "teste",
                KmRepasse = 1,
                Representante = "um",
                ValorRepasse = 2
            }
        };



        var Detalhes = new List<DetalhesExcel>() {
                new DetalhesExcel()
                {
                    NumColunaInicial = 23,
                    Coluna1 = "Representante",
                    Coluna2 = "ValorRepasse",
                    Coluna3 = "KmRepasse"
                }
            }.Concat(ocorrencias.Where(x => x.Conclusao != "PRÓPRIO")
                            .GroupBy(x => x.Representante)
                            .Select(x => new DetalhesExcel
                            {
                                NumColunaInicial = 23,
                                Coluna1 = x.First().Representante,
                                Coluna2 = x.Sum(y => y.ValorRepasse).ToString(),
                                Coluna3 = x.Sum(y => y.KmRepasse).ToString()
                            }).ToList());

    }
}

public class Ocorrencia
{
    public string Conclusao { get; set; }
    public string Representante { get; set; }
    public int KmRepasse { get; set; }
    public int ValorRepasse { get; set; }
}

public class DetalhesExcel
{
    public int NumColunaInicial { get; set; }
    public string Coluna1 { get; set; }
    public string Coluna2 { get; set; }
    public string Coluna3 { get; set; }
    public string Coluna4 { get; set; }
    public string Coluna5 { get; set; }
}

【讨论】：

@Taian 很好，很高兴为您提供帮助

【解决方案2】：

AddRange 返回无效。从而将List初始化和AddRange一分为二。

Detalhes = new List<DetalhesExcel>() {
    new DetalhesExcel()
    {
        NumColunaInicial = 23,
        Coluna1 = "Representante",
        Coluna2 = "ValorRepasse",
        Coluna3 = "KmRepasse"
    }
};

Detalhes.AddRange(ocorrencias.Where(x => x.Conclusao != "PRÓPRIO")
    .GroupBy(x => x.Representante)
    .Select(x => new DetalhesExcel
    {
        NumColunaInicial = 23,
        Coluna1 = x.First().Representante,
        Coluna2 = x.Sum(y => y.ValorRepasse).ToString(),
        Coluna3 = x.Sum(y => y.KmRepasse).ToString()
    }).ToList())

【讨论】：

没有办法“合并”它们吗？ “Detalhes”是另一个对象的属性，我不想把它分开。

【解决方案3】：

由于AddRange 修改了现有序列并返回void，因此它不能在方法链中作为赋值的一部分使用。但是，您可以使用Concat 方法，该方法通过将第一个与第二个连接起来创建一个新序列，然后返回该新序列：

Detalhes = new List<DetalhesExcel>()
{
    new DetalhesExcel()
    {
        NumColunaInicial = 23,
        Coluna1 = "Representante",
        Coluna2 = "ValorRepasse",
        Coluna3 = "KmRepasse"
    }
}.Concat(ocorrencias.Where(x => x.Conclusao != "PRÓPRIO")
    .GroupBy(x => x.Representante)
    .Select(x => new DetalhesExcel
    {
        NumColunaInicial = 23,
        Coluna1 = x.First().Representante,
        Coluna2 = x.Sum(y => y.ValorRepasse).ToString(),
        Coluna3 = x.Sum(y => y.KmRepasse).ToString()
    }).ToList());

【讨论】：

【解决方案4】：

AddRange() 返回void，这是您在list 上应用的最后一种方法。您不能将其分配给 list。

Detalhes = new List<DetalhesExcel>() {
    new DetalhesExcel()
    {
        NumColunaInicial = 23,
        Coluna1 = "Representante",
        Coluna2 = "ValorRepasse",
        Coluna3 = "KmRepasse"
    }
};
Detalhes.AddRange(ocorrencias.Where(x => x.Conclusao != "PRÓPRIO")
        .GroupBy(x => x.Representante)
        .Select(x => new DetalhesExcel
        {
            NumColunaInicial = 23,
            Coluna1 = x.First().Representante,
            Coluna2 = x.Sum(y => y.ValorRepasse).ToString(),
            Coluna3 = x.Sum(y => y.KmRepasse).ToString()
        }).ToList())

【讨论】：

【解决方案5】：

根据您对 Simonare 回答的评论，您是否尝试过这样做

Detalhes = new List<DetalhesExcel>(ocorrencias.Where(x => x.Conclusao != "PRÓPRIO")
    .GroupBy(x => x.Representante)
    .Select(x => new DetalhesExcel
    {
        NumColunaInicial = 23,
        Coluna1 = x.First().Representante,
        Coluna2 = x.Sum(y => y.ValorRepasse).ToString(),
        Coluna3 = x.Sum(y => y.KmRepasse).ToString()
    }).ToList())
    {
    new DetalhesExcel()
    {
        NumColunaInicial = 23,
        Coluna1 = "Representante",
        Coluna2 = "ValorRepasse",
        Coluna3 = "KmRepasse"
    }
    };

基本上使用基于列表的构造函数中的选定列表

【讨论】：