C# LINQ 返回泛型列表

Question

下面是我采样的两个类。不使用元组；我想将查询直接从第一个列表发送到第二个结果列表。

编码失败的部分显示为转换操作。

感谢您抽空回复。

        static void Main(string[] args)
    {

        List<liste> personel = new List<liste>{

            new liste { PersonId = 1, Name = "Burak", Surname = "Şenyurt", City = "İstanbul", Salary = 890 },
            new liste { PersonId = 2, Name = "Maykıl", Surname = "Cordın", City = "Chicago", Salary = 930 },
            new liste { PersonId = 3, Name = "Şakiyıl", Surname = "Oniyıl", City = "Los Angles", Salary = 986 },
            new liste { PersonId = 4, Name = "Ümit", Surname = "Oniyıl", City = "Los Angles", Salary = 1035 },
            new liste { PersonId = 5, Name = "Mehmet", Surname = "Zaferoğlu", City = "Los Angles", Salary = 1265 },
            new liste { PersonId = 6, Name = "Hasan", Surname = "Orkun", City = "Los Angles", Salary = 1435 },
            new liste { PersonId = 7, Name = "Raşit", Surname = "Mesut", City = "Los Angles", Salary = 1469 },
            new liste { PersonId = 8, Name = "Hamdi", Surname = "Tanpınar", City = "Los Angles", Salary = 1535 },
            new liste { PersonId = 9, Name = "Şevki", Surname = "Çapkın", City = "Los Angles", Salary = 1636 },
            new liste { PersonId = 10, Name = "Özhun", Surname = "Bozkurt", City = "Los Angles", Salary = 1839 }
        };
        double resAVG = personel.Select(x => x.Salary).Average();
        List<Sonuc> reportResult = GetReport(personel,resAVG);
    }

静态方法

        public static List<Sonuc> GetReport(List<liste> listePersonel , double resAVG)
    {
        List<Sonuc> result = (from e in listePersonel
                      where e.Salary >= resAVG
                      orderby e.Salary descending
                    //select new Tuple<string, string, double>(e.Name, e.Surname, e.Salary)).ToList<Tuple<string, string, double>>();
        select new List<Sonuc>(e.Name, e.Surname, e.Salary)).ToList<Sonuc>(result.ToList());

        return result;
    }

普通类

   public class liste
{
    public int          PersonId        { get; set; }
    public string       Name            { get; set; }
    public string       Surname         { get; set; }
    public string       City            { get; set; }
    public double       Salary          { get; set; }

    public override string ToString()
    {
        return $"PersonId : {PersonId}\t\tName , Surname {Name} , {Surname}\t\t\tSalary : {Salary}";
    }
}

结果类

    public class Sonuc
{
    public string       Name            { get; set; }
    public string       Surname         { get; set; }
    public double       Salary          { get; set; }

    public Sonuc(string Name , string Surname, double Salary)
    {
        this.Name = Name;
        this.Surname = Surname;
        this.Salary = Salary;
    }

    public override string ToString()
    {
        return $"Name, SurName : {this.Name} ,   {this.Surname}\t\t\tSalary : {this.Salary}";
    }
}

Answer 1

您正在尝试构建 List<T> 的实例通过传递一个 string , 一个 string , 和一个 double . List<T>没有采用这些参数的构造函数。此外，您不能使用 result在你分配它之前。

相反，您应该将每个项目投影到 listePersonel 中到 Sounc 的单个实例, 然后把那个可枚举的 List<Sounc> .

public static List<Sonuc> GetReport(List<liste> listePersonel , double resAVG)
{
    List<Sonuc> result = (from e in listePersonel
                  where e.Salary >= resAVG
                  orderby e.Salary descending
                  select new Sonuc(e.Name, e.Surname, e.Salary)).ToList();

    return result;
}