2 
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)})

我无法从以下代码将上述结果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))

原始课程如下所示。该类还有许多字符串属性，我在此代码段中省略了这些属性。所有这些属性也用于上述 linq 代码的分组中。：

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：

System.InvalidCastException 被捕获 Message="Unable to cast object of type 'WhereSelectEnumerableIterator 2[VB$AnonymousType_12[VB$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.IEnumerable1[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.Dictionary2[System.Int32,System.Double]]]' 类型为 'System. Collections.Generic.List`1[Addin.EntityTableRow]'。”

4

1 回答 1

1

你必须在那里做两件事：

创建结果时设置你的类名：

Into Group Select New EntityTableRow With { _

代替：

Into Group Select New With { _

并添加ToList()枚举并将结果放入List<EntityTableRow>：

myTable1_grouped.TableRows = CType(lFinal2.ToList(), List(Of EntityTableRow))
于 2013-03-19T19:48:10.947 回答