Relate two objects

Question

Hallo,

for example I have two list. Let say if have same IDs in both lists how can i select automatically the object in the Details list according to the object selected in the Sample list from binding source. I know using LINQ i can get the values i want , is there any other way so i can refer to something like CType(ID, Details).Description ?

Public Class  Sample1

Public Property ID as Integer
Public Property Item as String

End Class

Public Class  Details

Public Property ID as Integer
Public Property Description as String

End Class

Thanks

Answer 1

Key here is join and group e.g. conceptual/working example done in a form for ease of coding.

Public Class Form1
    Private Sub SampleButton_Click(sender As Object, e As EventArgs) Handles SampleButton.Click

        Dim sampleList = Mocked.Sample1List()
        Dim detailList = Mocked.DetailsList()

        Dim joinedResults = (
                From sampleItem In sampleList 
                Join detailItem In detailList On detailItem.Sample1Id Equals sampleItem.ID 
                Select New Result With {
                    .Id = sampleItem.ID, 
                    .Item = sampleItem.Item, 
                    .Description = detailItem.Description}
        ).ToList()

        Dim grouped = joinedResults.GroupBy(Function(result) result.Id).ToList()

        For Each grouping As IGrouping(Of Integer, Result) In grouped
            Console.WriteLine(grouping.Key)
            For Each item As Result In grouping
                Console.WriteLine($"    {item.Description}")
            Next
        Next

        Console.WriteLine()

        Console.WriteLine("Get id 2 items")
        Dim singleResult As IEnumerable(Of Result) = grouped.Select(Function(grouped) grouped).FirstOrDefault(Function(item) item.Key = 2)
        For Each result As Result In singleResult
            Console.WriteLine($"    {result.Description}")
        Next
    End Sub
End Class

Public Class Result
    Public Property Id As Integer
    Public Property Item As String
    Public Property Description As String
End Class

Public Class Sample1
    Public Property ID As Integer
    Public Property Item As String
End Class

Public Class Details
    Public Property ID As Integer
    Public Property Sample1Id As Integer
    Public Property Description As String
End Class

Public Class Mocked
    Public Shared Function Sample1List() As List(Of Sample1)
        Return New List(Of Sample1) From {
            New Sample1() With {.ID = 1, .Item = "A"},
            New Sample1() With {.ID = 2, .Item = "B"},
            New Sample1() With {.ID = 3, .Item = "C"}
        }
    End Function
    Public Shared Function DetailsList() As List(Of Details)
        Return New List(Of Details) From {
            New Details() With {.ID = 1, .Sample1Id = 1, .Description = "1st"},
            New Details() With {.ID = 2, .Sample1Id = 1, .Description = "2nd"},
            New Details() With {.ID = 3, .Sample1Id = 1, .Description = "3rd"},
            New Details() With {.ID = 4, .Sample1Id = 2, .Description = "111"},
            New Details() With {.ID = 5, .Sample1Id = 2, .Description = "222"},
            New Details() With {.ID = 6, .Sample1Id = 3, .Description = "111"}
        }
    End Function
End Class

Results

1
    1st
    2nd
    3rd
2
    111
    222
3
    111

Get id 2 items
    111
    222