Question

I have a dynamic webpage that loads a user control multiple times, including loading the user control within itself as many times as needed. Within the user control there are four controls: Title Label, Repeater, Placeholder and within Repeater a AjaxControlToolkit Rating control.

The structure can look like the following:

Webpage
  Placeholder
    UserControl (repeater hidden, no data)
      Placeholder - [UserControl]
        UserControl
          Repeater
            RepeaterItem - [RatingControl]
            RepeaterItem - [RatingControl]
          Placeholder - [UserControl]
            UserControl (placeholder hidden, no data)
              Repeater
                RepeaterItem - [RatingControl]
                RepeaterItem - [RatingControl]
    UserControl
      Repeater
        RepeaterItem - [RatingControl]
        RepeaterItem - [RatingControl]
      Placeholder - [UserControl]
        UserControl (placeholder hidden, no data)          
          Repeater
            RepeaterItem - [RatingControl]

Here is my recursive method:

Protected Sub Get_Ratings(ByVal ctl As Control, ByVal grouptotal As Integer)
    If TypeOf ctl Is PerformanceEvaluationSubcontractorControl Then
        Dim pesctl As Control
        For Each pesctl In ctl.Controls
            If TypeOf pesctl Is PerformanceEvaluationSubcontractorControl Then
                Me.Get_Ratings(pesctl, grouptotal)
            ElseIf pesctl.Controls.Count > 0 Then
                Dim spesctl As Control
                For Each spesctl In pesctl.Controls
                    If TypeOf spesctl Is Repeater Then
                        Dim rptctl As Control
                        For Each rptctl In spesctl.Controls
                            Me.Get_Ratings(pesctl, grouptotal)
                        Next
                    End If
                    If TypeOf spesctl Is PlaceHolder Then
                        Dim plhctl As Control
                        For Each plhctl In spesctl.Controls
                            Me.Get_Ratings(plhctl, grouptotal)
                        Next
                    End If
                Next
            ElseIf TypeOf pesctl Is AjaxControlToolkit.Rating Then
                Dim ajrating As AjaxControlToolkit.Rating = pesctl
                grouptotal = grouptotal + ajrating.CurrentRating
            End If
        Next
    ElseIf ctl.Controls.Count > 0 Then
        Dim sctl As Control
        For Each sctl In ctl.Controls
            Me.Get_Ratings(sctl, grouptotal)
        Next
    End If
End Sub

My question is, how do I efficiently loop through this type of structure to find the rating controls?

Answer 1

Sorry, my VB.NET isn’t all that great, but wouldn’t a recursive function look similar to:

Protected Function GetRatings(ByVal control As Control) As IEnumerable(Of AjaxControlToolkit.Rating)
  If (control.Controls.Count > 0) Then
    Dim result As New List(Of AjaxControlToolkit.Rating)()

    For Each child In Control.Controls
      Dim rating As AjaxControlToolkit.Rating = child As AjaxControlToolkit.Rating
      If Not (rating Is Nothing) Then
        result.Add(rating)
      Else
        result.AddRange(GetRatings(child))
      End If  
    Next

    Return result
  Else
    Return Enumerable.Empty(Of AjaxControlToolkit.Rating)()
  End If
End Function

Couldn’t you then do a summation:

Dim controls As IEnumerable(Of AjaxControlToolkit.Rating) = GetRatings(control)
Dim total As Int32 = Enumerable.Sum(Of AjaxControlToolkit.Rating)(_
    controls, Function(rating) rating.CurrentRating)

If the syntax is way off, let me know, I don’t normally do VB.NET