在VB.NET中通过LINQ对通用列表进行分组 [英] Grouping a generic list via LINQ in VB.NET

问题描述

我需要收集一个集合并通过Linq对其进行分组，但是我所看到的所有示例都以某种方式或其他方式失败，但语法上有些差异，我不太喜欢.

I need to take a collection and group it via Linq but all the examples I've seen fail in some manner or other with some syntax difference that I can't quite lick.

我的收藏集:

Dim a As New List(Of ProcessAlert)
  a.Add(New ProcessAlert("0000112367", "[e-mail]", "Alert", 2))
  a.Add(New ProcessAlert("0000112367", "[e-mail]", "Document", 2))
  a.Add(New ProcessAlert("0000112367", "[e-mail]", "Note", 2))
  a.Add(New ProcessAlert("0000112367", "[e-mail]", "Alert", 1))
  a.Add(New ProcessAlert("0000112367", "[e-mail]", "Document", 1))
  a.Add(New ProcessAlert("0000112367", "[e-mail]", "Note", 1))
Return a

我需要将这个收藏集变成一种简单的方法来获得最终结果:

I need to turn this collection into a simple way to give this final outcome:

"[e-mail]", "Alert, Document, Note"
"[e-mail]", "Alert, Document, Note"

这是ProcessAlert类的定义:

Public Class ProcessAlert
  Public LoanNumber As String
  Public EmailAddress As String
  Public AlertType As String
  Public AlertMethodID As Byte
End Class

预先感谢

CD

我设法转换为VB:

    Dim res = Alerts.GroupBy(Function(i) i.EmailAddress).Select(Function(g) New KeyValuePair(Of String, String)(g.Key, String.Join(",", g.Select(Function(x) x.AlertType).ToArray())))

现在如何将LoanNumber和电子邮件地址添加到组中，这样我的结果是: "0000112367"，"[e-mail]"，警报，文档，注释"

Now how do I add in to group by LoanNumber and Email Address so that my result is: "0000112367","[e-mail]", "Alert, Document, Note"

推荐答案

这是我要编写的linq代码(在C#中-很抱歉，我无法在VB中完成它)

Here is the linq code I would write (in c# - sorry I couldn't complete it in VB)

var res = a.GroupBy(i=>i.EmailAddress )
    .Select(g=> new KeyValuePair<string, string>(
                    g.Key, 
                    string.Join(",", g.Select(x=> x.AlertType ).ToArray()) 
            ));

这将在KeyValuePair集合中为您提供所需的输出

This will give you the output you want in a collection of KeyValuePair

为了将它们分别按LoadNumber和EmailAddress进行分组，这将是c#代码:

in order to group them by both LoadNumber and EmailAddress this would be the c# code:

var res = alerts
    .GroupBy(a => new { L = a.LoanNumber, E = a.EmailAddress })
    .Select(a => new
        {
            LoadNumber = a.Key.L,
            EmailAddress = a.Key.E,
            Types = string.Join(", ", a.Select(x => x.AlertType).ToArray())
        }).ToList();

其中的结果是Complext类型{LoadNumber，EmailAddress，类型}的列表

where result is a List of a Complext type {LoadNumber, EmailAddress, Types}

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