如何在 linq vb 组加入中订购内部密钥源

Question

我正在尝试使用组连接和 VB.NET 将表连接到自身。下面的代码可以工作并对外部（父）行进行排序，但我想保证内部（子）行的顺序：

Dim queryEthnicities = From aParentEthnicity In edata.Ethnicity _
   Group Join aChildEthnicity In edata.Ethnicity On aChildEthnicity.ParentID Equals aParentEthnicity.EthnicityID Into EthnicityList = Group _
   Where aParentEthnicity.RoundID.Equals(aRoundID) Order By aParentEthnicity.Sort

我在Ordering inner keysource in simple/unnamed C# LINQ group join 找到了与 C# 类似的东西 但还没有找到在 VB 中执行此操作的方法 - 感谢任何想法。

Answer 1

您在提问时需要提供以下信息：

Public Class edata

    Public Ethnicity As Ethnicity() = _
    { _
        New Ethnicity() With { .EthnicityID = 4, .ParentId = 1, .RoundID = 3, .Sort = 8 }, _
        New Ethnicity() With { .EthnicityID = 3, .ParentId = 1, .RoundID = 4, .Sort = 5 }, _
        New Ethnicity() With { .EthnicityID = 1, .RoundID = 2 } _
    }

End Class

Public Class Ethnicity

    Public ParentID As Integer
    Public EthnicityID As Integer
    Public RoundID As Integer
    Public Sort As Integer

End Class

Sub Main

    Dim edata = New edata()
    Dim aRoundID = 2

    Dim queryEthnicities = _
        From aParentEthnicity In edata.Ethnicity _
        Group Join aChildEthnicity In edata.Ethnicity On aChildEthnicity.ParentID Equals aParentEthnicity.EthnicityID Into EthnicityList = Group _
        Where aParentEthnicity.RoundID.Equals(aRoundID) _
        Order By aParentEthnicity.Sort

End Sub

当这段代码运行时，它会产生：

为确保内部数据的顺序，您需要像这样更改查询：

Dim queryEthnicities = _
    From aParentEthnicity In edata.Ethnicity _
    Group Join aChildEthnicity In edata.Ethnicity.OrderBy(Function (x) x.Sort) On aChildEthnicity.ParentID Equals aParentEthnicity.EthnicityID Into EthnicityList = Group _
    Where aParentEthnicity.RoundID.Equals(aRoundID) _
    Order By aParentEthnicity.Sort

现在它产生了：