Question

尝试做一些我确信应该很简单的事情，但是要努力学习linq和VB。我有下面的内容，我正在将一个集合分组，然后想要访问我的组的属性。我遇到的问题是匿名输入。由于选项严格，我必须给出一个显式类型，但我无法确定类型应该是什么。下面没有编译，因为t.HeadAccountKey不是一个值（因为t有一种对象）。所以要么我需要做一些演员，要么我的linq选择器是错的，

public class TempObject
    public HeadKey as string
    Public SubKey as string
    Public SomeValue as decimal
end class

public class GroupTest
public sub RunTest
    dim collection new List(of TempObject) = GetTestCollection()

    Dim groupedValues As IEnumerable = From n In collection _
        Group By key = n.HeadKey Into Group Select HeadKeyValue = key, SubValues = Group

    for each t as object in groupedValues
    debug.print(t.HeadKeyValue)
        next

End sub

private function GetTestCollection() as List(of TempObject)
    dim result as new list(of tempobject)
    Dim x As New tempObject
    x.HeadAccountNumber = "A"
        x.SubAccountNumber = "B"
        x.Value = 500
        result.Add(x)
        x = New tempObject
        x.HeadAccountNumber = "A"
        x.SubAccountNumber = "C"
        x.Value = 600
        result.Add(x)
        x = New tempObject
        x.HeadAccountNumber = "B"
        x.SubAccountNumber = "D"
        x.Value = 100
    result.add(x)
    return result
end function
End class

Answer 1

您不需要指定类型，至少使用Option Infer on（可推荐，不要与Option Strict混淆）。

以下作品：

Dim collection = GetTestCollection()
Dim groupedValues = From n In collection
    Group n By n.HeadKey Into Group

For Each t In groupedValues
    Dim hk = t.HeadKey
    Dim group = t.Group
Next

Linq Grouping在VB.net中使用匿名类型和选项严格

1 个答案: