UWP中ListView的Item绑定ViewModel的成员变量

<ListView x:Name="OrdersListView" ItemsSource="{Binding Orders}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <ProgressRing IsActive="{Binding DataContext.IsLoading, ElementName=OrdersListView}" />
            </StackPanel>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>