LinQ 结果进入列表

Question

我有以下类作为列表;

class list_TA

{

    public DateTime SAMPLE_TIME { get; set; }

    public string WAIT_CLASS { get; set; }

    public double COUNT { get; set; }

    public list_TA(DateTime SAMPLE_TIME, string WAIT_CLASS,double COUNT)

    {

        this.SAMPLE_TIME = SAMPLE_TIME;

        this.WAIT_CLASS = WAIT_CLASS;

        this.COUNT = COUNT;

    }

}

//SECOND PART

                 var test = listASH

                          .Select(g => new

                          {

                              SAMPLE_TIME = statiClass.By15Seconds(Convert.ToDateTime(g.SAMPLE_TIME)),

                              WAIT_CLASS = g.WAIT_CLASS,

                              COUNT = 0,

                          }).GroupBy(x => new { x.SAMPLE_TIME, x.WAIT_CLASS })

                          .Select(y => new

                          {

                              SAMPLE_TIME = y.Key.SAMPLE_TIME,

                              WAIT_CLASS = y.Key.WAIT_CLASS,

                              COUNT = Math.Round(y.Count() / 15.0, 2),

                          });

我想要的是将linq结果加载到list_TA中。但是下面的代码不起作用，它给出了以下错误;

 List<list_TA> lst = (List<list_TA>)test.ToList(); 

错误;

Cannot convert type 'System.Collections.Generic.List<<anonymous type: System.DateTime SAMPLE_TIME, string WAIT_CLASS, double COUNT>>' to 'System.Collections.Generic.List<vodaMon.list_TA>'

正在转换为列表（）;不起作用。

Answer 1

也使用代替任意值类型：当您实例化list_TA时，它需要DateTime SAMPLE_TIME，字符串WAIT_CLASS，双倍计数作为参数传递。为了解决这个问题，请引入无参数构造函数。new list_TA&nbsp;public class list_TA{&nbsp; &nbsp; public DateTime SAMPLE_TIME { get; set; }&nbsp; &nbsp; public string WAIT_CLASS { get; set; }&nbsp; &nbsp; public double COUNT { get; set; }&nbsp; &nbsp; public list_TA()&nbsp; &nbsp; {&nbsp; &nbsp; }&nbsp; &nbsp; public list_TA(DateTime SAMPLE_TIME, string WAIT_CLASS, double COUNT)&nbsp;&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; this.SAMPLE_TIME = SAMPLE_TIME;&nbsp; &nbsp; &nbsp; &nbsp; this.WAIT_CLASS = WAIT_CLASS;&nbsp; &nbsp; &nbsp; &nbsp; this.COUNT = COUNT;&nbsp; &nbsp; }}

Answer 2

您可以在 LINQ 中选择list_TA，如下所示：var test = listASH&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .Select(g => new&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; SAMPLE_TIME = statiClass.By15Seconds(Convert.ToDateTime(g.SAMPLE_TIME)),&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; WAIT_CLASS = g.WAIT_CLASS,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; COUNT = 0,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }).GroupBy(x => new { x.SAMPLE_TIME, x.WAIT_CLASS })&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; .Select(y => new list_TA&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; SAMPLE_TIME = y.Key.SAMPLE_TIME,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; WAIT_CLASS = y.Key.WAIT_CLASS,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; COUNT = Math.Round(y.Count() / 15.0, 2),&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }).ToList();

Answer 3

匿名类不能隐式转换为任何其他类型。您需要使用而不是new list_TAnew将默认构造函数添加到类中，并使用以下代码list_TA&nbsp; .Select(y => new list_TA&nbsp; {&nbsp; &nbsp; &nbsp; SAMPLE_TIME = y.Key.SAMPLE_TIME,&nbsp; &nbsp; &nbsp; WAIT_CLASS = y.Key.WAIT_CLASS,&nbsp; &nbsp; &nbsp; COUNT = Math.Round(y.Count() / 15.0, 2),&nbsp; });或&nbsp; .Select(y => new list_TA (&nbsp; &nbsp; &nbsp; y.Key.SAMPLE_TIME,&nbsp; &nbsp; &nbsp; y.Key.WAIT_CLASS,&nbsp; &nbsp; &nbsp; Math.Round(y.Count() / 15.0, 2)&nbsp; &nbsp;));