Windows 8.1至10 XAML-参数不正确的异常

Question

I have a Windows 8.1 app that runs fine in Windows 8.1, but when running on a Windows 10 machine, I encounter a XAML exception, with the unhandled exception message, "The parameter is incorrect."

When I change the debugger type to mixed (managed and native), the exception message is "Value does not fall within the expected range."

Original XAML

<ListView x:Name="myListView"
      Grid.Row="3"
      Margin="10"
      HorizontalAlignment="Center"
      VerticalAlignment="Top"
      BorderBrush="Gray"
      BorderThickness="1"
      FontSize="{StaticResource FontSizeMedium}"
      ItemsSource="{Binding LookupList}">
<ListView.ItemTemplate>
    <DataTemplate>
        <Grid Width="{Binding DataContext.ColumnWidth, ElementName=myListView}" Visibility="{Binding IsVisible, Converter={StaticResource BooleanToVisibilityConverter}}">
            <ListView Name="gridList"
                      Grid.Row="1"
                      VerticalAlignment="Top"
                      FontSize="{StaticResource FontSizeMedium}"
                      ItemsSource="{Binding ColumnValues}"
                      SelectedIndex="{Binding DataContext.SelectedIndex,
                                              Mode=TwoWay,
                                              ElementName=myListView}"
                      SelectionMode="Single">
            </ListView>
        </Grid>
    </DataTemplate>
</ListView.ItemTemplate>
</ListView>

If I remove the ElementName in the SelectedIndex binding, the list view loads (but does not have the correct functionality).

Modified XAML (loads without exception, but not the correct functionality)

<ListView x:Name="myListView"
      Grid.Row="3"
      Margin="10"
      HorizontalAlignment="Center"
      VerticalAlignment="Top"
      BorderBrush="Gray"
      BorderThickness="1"
      FontSize="{StaticResource FontSizeMedium}"
      ItemsSource="{Binding LookupList}">
<ListView.ItemTemplate>
    <DataTemplate>
        <Grid Width="{Binding DataContext.ColumnWidth, ElementName=myListView}" Visibility="{Binding IsVisible, Converter={StaticResource BooleanToVisibilityConverter}}">
            <ListView Name="gridList"
                      Grid.Row="1"
                      VerticalAlignment="Top"
                      FontSize="{StaticResource FontSizeMedium}"
                      ItemsSource="{Binding ColumnValues}"
                      SelectedIndex="{Binding DataContext.SelectedIndex,
                                              Mode=TwoWay}"
                      SelectionMode="Single">
            </ListView>
        </Grid>
    </DataTemplate>
</ListView.ItemTemplate>
</ListView>

Is ElementName binding in this manner still supported, or are there additional debugging steps that can yield more information?

Answer 1

I am surprised that it's even working in Windows Phone 8.1 because the binding is incorrect.

This binding expression {Binding DataContext.SelectedIndex, Mode=TwoWay, ElementName=myListView} here basically means to go locate a control named myListView and then find a property called SelectedIndex of the control's DataContext (which is in most case, the ViewModel ).

But really the SelectedIndex should be the dependency property of the ListView control .

So the fix is simple - just remove the DataContext. -

SelectedIndex="{Binding SelectedIndex, Mode=TwoWay, ElementName=myListView}"

Answer 2

To access the items container for your itemtemplate, you have to use RelativeSource to find the ancestor that contains your item template.

In your example, it would mean defining this kind of binding

SelectedIndex="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListView}}, Path=SelectedIndex,Mode=TwoWay}"