Simplify Your Code with Reflection: Listing 3: VB.NET, Retrieve Property Values

You can use the GetControls method to determine which method to use to retrieve property values. GetControls is responsible for looping through the controls on your form and getting the data from each control. The data is retrieved by calling a method named GetControlValue or GetMultiListValues in the case of a multiple-selection list. The GetControlValue method is the one that uses reflection to retrieve the value.

Private Function GetControls( _
   ByVal ctls As Control.ControlCollection) As String
   Dim sb As New System.Text.StringBuilder(1024)
   Dim dc As DirtyControl

   For Each ctl As Control In ctls
      If ctl.HasChildren Then
         ' Recurse into any "Grouping" controls
         sb.Append(GetControls(ctl.Controls))
      End If

      ' Get DirtyControl Definition
      dc = AppConfig.DirtyControlsList.GetByType( _
         ctl.GetType().ToString())
      If dc IsNot Nothing Then
         If dc.IsMultiList And _
            dc.PropertyToCheck = _
            String.Empty Then
            sb.Append(GetMultiListValues( _
               CType(ctl, ListBox)))
         ElseIf dc.IsMultiList And _
            dc.PropertyToCheck <> String.Empty Then
            If GetControlValue(ctl, dc.PropertyToCheck) = _
               sb.Append(GetControlValue( _
               ctl, dc.Property1))
            Else
               sb.Append(GetMultiListValues( _
                    CType(ctl, ListBox)))
            End If
         ElseIf dc.IsMultiList = False And _
            dc.PropertyToCheck <> String.Empty Then
            If GetControlValue(ctl, dc.PropertyToCheck) = _
               dc.PropertyToCheckValue Then
               sb.Append(GetControlValue( _
                    ctl, dc.Property1))
            Else
               sb.Append(GetControlValue( _
                    ctl, dc.Property2))
            End If
         ElseIf dc.IsMultiList = False And _
            dc.Property2 <> String.Empty Then
            sb.Append(GetControlValue(ctl, dc.Property1))
            sb.Append(GetControlValue(ctl, dc.Property2))
         Else
            sb.Append(GetControlValue(ctl, dc.Property1))
         End If
      End If
   Next

   Return sb.ToString()
End Function
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