Question

Dim a As New List(Of EntityTableRow)
            a = myTable1.TableRows

            Dim lFinal2 = (From el In a Group el By Key = New With {Key el.Description, Key el.Activity, Key el.ServiceGroup, Key el.SubServiceGroup, Key el.ResourceGroup, Key el.Country, Key el.DCN, Key el.Workforce, Key el.RateType, Key el.LoadType} _
                              Into Group Select New With { _
                              .PageNum = "", _
                              .Description = Key.Description, _
                              .Activity = Key.Activity, _
                              .MonthCosts = (From k In Group.SelectMany(Function(g) g.MonthCosts.Keys).Distinct() _
                                            Select New With {.Month = k, .Sum = Group.Sum(Function(g) _
                                        If(g.MonthCosts.ContainsKey(k), g.MonthCosts(k), 0))}).ToDictionary(Function(i) i.Month, Function(i) i.Sum)})

我无法将上述结果从以下代码转换回原始对象形式：

    Dim myTable1_grouped As New EntityDATATable(Of EntityTableRow) 
    myTable1_grouped.TableRows = CType(lFinal2, List(Of EntityTableRow))

原始课程如下。该类有许多字符串属性，我已为此代码段省略了这些属性。所有这些属性也在上面的linq代码中使用分组。：

Public Class EntityTableRow
    Public PageNum As Integer
    Public Description As String
    Public Activity As String
    .....
    .....
    .....
    Public MonthCosts As New Dictionary(Of Integer, Double)
End Class

我得到的错误是：

发现了System.InvalidCastException Message =“无法转换类型的对象'WhereSelectEnumerableIterator 2[VB$AnonymousType_1 2 [VB $ AnonymousType_0 10[System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String],System.Collections.Generic.IEnumerable 1 [Addin.EntityTableRow]]，VB $ AnonymousType_2 35[System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.Collections.Generic.Dictionary 2 [System.Int32，System。 Double]]]'键入'System.Collections.Generic.List`1 [Addin.EntityTableRow]'。“

Answer 1

你必须做两件事：

创建结果时设置您的班级名称：

Into Group Select New EntityTableRow With { _

而不是：

Into Group Select New With { _

添加ToList()枚举并将结果导入List<EntityTableRow>：

myTable1_grouped.TableRows = CType(lFinal2.ToList(), List(Of EntityTableRow))

如何将结果转换回通用列表（使用linq对象）？

1 个答案: