Unexpected InvalidCastException With DataTemplate

Question

I have the following Xaml for which I set the ItemsSource property as follows:
<ItemsControl x:Name="itmRecipients" Grid.Column="0" Grid.Row="2" ScrollViewer.VerticalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollMode="Auto" ScrollViewer.BringIntoViewOnFocusChange="True">
<ItemsControl.ItemsPanel><ItemsPanelTemplate><StackPanel/></ItemsPanelTemplate></ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate><DataTemplate><RadioButton Style="{StaticResource BasicToggleButton}" GroupName="Recipients" Checked="Recipient_Checked" Content="{Binding Name}" Tag="{Binding Index}"/></DataTemplate></ItemsControl.ItemTemplate>
</ItemsControl>
Me.itmRecipients.ItemsSource = Me.Recipients.Select(Function(r, i) New With {.Name = r.Name, .Index = i})
As you can see, the DataTemplate is just a RadioButton which uses the Name and Index properties of the bound items. The bound items are an anonymous type with the properties Name and Index. But when I run the code, I get the following error:
A first chance exception of type 'System.InvalidCastException' occurred in GiftTrackerUnivAppTest_Windows.exe
After looking at App.g.i.vb, I found the following in unhandledExceptionArgs:
"System.InvalidCastException: Unable to cast object of type 'VB$AnonymousType_0`2[System.String,System.Int32]' to type 'Windows.UI.Xaml.Controls.RadioButton'.
    at GiftTrackerUnivAppTest_Windows.MainPage.MainPage_Loaded(Object sender, RoutedEventArgs e)"
'VB$AnonymousType_0`2[System.String,System.Int32]' is obviously my anonymous type with the Name and Index properties. Why is it trying to convert my anonymous type to a RadioButton instead of applying it to the DataTemplate? Thanks.
Nathan Sokalski [email protected] http://www.nathansokalski.com/

Answer 1

Hi Nathan,
I used the following code snippet to test in store app, but I worked. I could not reproduce your problem. Can you post a repro project or post more information to explain your scenario?
Private Sub Page_Loaded(sender As Object, e As RoutedEventArgs)
list = New System.Collections.ObjectModel.ObservableCollection(Of Employee)()
Dim rnd As New Random()
For i As Integer = 0 To 99
Dim ee As New Employee()
ee.Name = "herro" & i.ToString()
ee.Index = rnd.Next(0, 101)
list.Add(ee)
Next
itmRecipients.ItemsSource = list.Where(Function(w) w.Index > 10).[Select](Function(s) New With { _
Key .Name = s.Name, _
Key .Index = s.Index _
End Sub
Regards,
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