C# 由“etc”组成的“x”组做什么？

虽然我在MSDN和许多书中搜索过，但我找不到任何关于这种查询的帮助。也许这里有人能帮我。下面是一个例子：

 var query = from document in Database.Documents                           
                       group document.OwnerID by 
                       new 
                       { 
                           OwnerName= document.Owner.OwnerName,
                           ReleaseDate= document.ReleaseDate,
                           OwnerID= document.OwnerID,
                           Status= document.StatusId

                       }
                       into grupo                               
                       select new AmountOfDocuments
                       {
                           OwnerName= grupo.Key.OwnerName,
                           ReleaseDate= grupo.Key.ReleaseDate,
                           OwnerID= grupo.Key.OwnerID,
                           UDocuments= grupo.Count(),
                           SDocuments= grupo.Count()
                       };

我需要让UDocuments和SDocuments返回状态分别为U或S的文档数。对此的帮助将不胜感激，但我需要弄清楚查询本身是如何工作的

---

提前谢谢

Lambda表达式是你的朋友

UDocuments = grupo.Where(x => x.Status == "U").Count(),
SDocuments = grupo.Where(x => x.Status == "S").Count()

编辑：不需要输入where

UDocuments = grupo.Count(x => x.Status == "U"),
SDocuments = grupo.Count(x => x.Status == "S")

---

检查在Linqpad中创建的以下代码，它以两种不同的方式完成任务并产生相同的结果。第二种方法更可取，因为它将状态作为分组值进行预测，因此计数变得更简单

void Main()
{
    var testList = Test.Create();

    var result = 
    testList.GroupBy(x=>new {
                          x.OwnerName,
                          x.OwnerId,
                          x.ReleaseDates
                            })
            .Select(y=>new {
                           y.Key.OwnerName,
                           y.Key.OwnerId,
                           statusU = y.Count(m=>m.status == "U"),
                           statusS = y.Count(m=>m.status == "S"),
                            });

    result.Dump();

    var result1 = 
    testList.GroupBy(x=>new {
                          x.OwnerName,
                          x.OwnerId,
                          x.ReleaseDates
                            },x=>x.status)
            .Select(y=>new {
                           y.Key.OwnerName,
                           y.Key.OwnerId,
                           statusU = y.Count(m=>m=="U"),
                           statusS = y.Count(m=>m=="S"),
                            });

    result1.Dump();
}

public class Test
{
    public string OwnerName {get; set;}

    public int OwnerId {get; set;}

    public string status {get; set;}

    public DateTime ReleaseDates{get; set;}

    public static List<Test> Create()
    {
      return new List<Test>()
        {

        new Test
        {
          OwnerName = "ABCD",
          OwnerId = 1,
          status = "S",
          ReleaseDates = DateTime.Now
        },
        new Test
        {
          OwnerName = "ABCD",
          OwnerId = 1,
          status = "S",
          ReleaseDates = DateTime.Now
        },
        new Test
        {
          OwnerName = "ABCD",
          OwnerId = 1,
          status = "S",
          ReleaseDates = DateTime.Now
        },
        new Test
        {
          OwnerName = "ABCD",
          OwnerId = 1,
          status = "U",
          ReleaseDates = DateTime.Now
        },
        new Test
        {
          OwnerName = "ABCD",
          OwnerId = 1,
          status = "U",
          ReleaseDates = DateTime.Now
        },
        new Test
        {
          OwnerName = "ABCD",
          OwnerId = 1,
          status = "S",
          ReleaseDates = DateTime.Now
        }

        };
    }   
}

---

您的意思是==not=并且Count接受一个谓词，因此更简单地说，grupo.Countx=>x.Status==Ux是作为int变量生成的，而不是作为AmountOfDocuments one.x不能是整数，除非您投影一个整数值，否则请检查该部分，在您的解决方案中，它应该是complete对象。查看如何在由创建的解决方案中进行项目me@StevenEccles您已确认但未更正其中的版本，请将其应具有的更正设置为==，当前格式为错误