Hierarchical Linq to sql query

Question

I am querying 2 result sets and need to return a nested result set with specific fields.  What is the best way to filter the nested fields out of the query.
Ex:
Dim oBallotMeasures = From ballot In dc.sp_SelectBallotMeasures(Nothing, id)
Group Join infoSources In dc.sp_SelectBallotMeasureInfo(Nothing, id)
On ballot.Measure_Id Equals infoSources.Measure_Id
Into MeasureInfo = Group
Select ballot.Measure_id, ballot.Name, MeasureInfo
MeasureInfo includes fields that I do not want to return.  How can I filter out some of the records, but keep the hierarchical structure?
Desired result:
[Measure_id: 1
Name: Name 1
MeasureInfo: [MeasureInfoName: 1
                    [MeasureInfoName: 2
[Measure_id: 2
Name: Name 2
MeasureInfo: [MeasureInfoName: 1
                    [MeasureInfoName: 2
Current result:
[Measure_id: 1
Name: Name 1
MeasureInfo: [MeasureInfoName: 1
                     MeasureInfoOtherInfo: xyz
                    [MeasureInfoName: 2
                     MeasureInfoOtherInfo: xyz
[Measure_id: 2
Name: Name 2
MeasureInfo: [MeasureInfoName: 1
                     MeasureInfoOtherInfo: xyz
                    [MeasureInfoName: 2
                     MeasureInfoOtherInfo: xyz
Also, is there any easier way to create a hierarchical result set?
RobertRFreeman

Answer 1

Hello RobertRFreeman,
From your description, it seems that your result sets will already be in local, so you could create DTO class to specify the returned column you want. For example,
DTO classes:
Public Class OrderDTO
Property OrderID As Integer
Property OrderName As String
Property OrderDetailName As Object
End Class
Public Class OrderDetailDTO
Property OrderDetailName As String
End Class
The LINQ query:
Using db As DFDBEntities1 = New DFDBEntities1
Dim result = (From o In db.Orders.ToList
Group Join od In db.OrderDetails.ToList On o.OrderID Equals od.OrderID
Into OOD = Group
Select New OrderDTO With {
.OrderID = o.OrderID,
.OrderName = o.OrderName,
.OrderDetailName = From oood In OOD
Select New OrderDetailDTO With {.OrderDetailName = oood.OrderDetailName}}).ToList
End Using
It will return OrderID, OrderName and a collection which contains OrderDetailName column only I want. Please have a try and note this approach is used LINQ to Objects, while for using LINQ to Entities, unfortunately, the LINQ to Entities does not support
such a cast.
Regards.
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