Question

documentation有一个关于对多个属性进行分组的示例：

Dim custRegionQuery = From cust In db.Customers _
    Group cust.ContactName By Key = New With _
        {cust.City, cust.Region} Into grouping = Group

For Each grp In custRegionQuery
    Console.WriteLine(vbNewLine & "Location Key: {0}", grp.Key)
    For Each listing In grp.grouping
        Console.WriteLine(vbTab & "{0}", listing)
    Next
Next

假设我有一个真实的类型（即非匿名），它具有键的每个元素的属性，以及组的属性，所以有点像：

Public Class CustomerRegionGroup

    Public Sub New(city As String, region as String, customers As IEnumerable(Of Customer))
        Me.City = city
        Me.Region = region
        Me.Customers = customers
    End Sub

    Public Property City As String
    Public Property Region As String
    Public Property Customers As IEnumerable(Of Customer)
End Class

是否可以将原始查询重写为仅返回IEnumerable(Of CustomerRegionGroup)，或者是否必须使用匿名类型，并对第一个查询的结果运行第二个查询？

Answer 1

事实证明这比我试过的一些事情要简单得多，因为我并不欣赏你能做到的事情：

Dim custRegionQuery = From cust In db.Customers _
                      Group By cust.City, cust.Region _
                      Into Group _
                      Select New CustomerRegionGroup(City, Region, Group)

如何在不使用匿名类型的情况下使用Linq实体对集合进行分组？

1 个答案: