How to reach SelectedItem in nested ListView

Question

I\'m wrestling with these last few days. I found lots of links, but none of them really helped me. I\'m quite a beginner in WPF. All I need is to reach SelectedItem property in

Answer 1

In

SelectedItem="{Binding Path=NestedSelectedItem,
               RelativeSource={RelativeSource AncestorType=vm:MainVM}, ...}

the type vm:MainVM is not an ancestor type of the inner ListView, because it not part of a visual or logical tree.

The AncestorType must be a UI element, e.g. the outer ListView. You would access the property by a nested property Path via its DataContext:

SelectedItem="{Binding Path=DataContext.NestedSelectedItem,
               RelativeSource={RelativeSource AncestorType=ListView}, ...}

---

As a note, since you are not setting the View property of the ListViews, you could as well use the simpler base class ListBox instead of ListView:

<ListBox ItemsSource="{Binding Path=SourceCollection}"
         SelectedItem="{Binding Path=OutterSelectedItem}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBlock Text="{Binding Title}"/>
                <TextBlock Text="Now second ListView:"/>
                <ListBox ItemsSource="{Binding Strings}"
                         SelectedItem="{Binding Path=DataContext.NestedSelectedItem,
                             RelativeSource={RelativeSource AncestorType=ListBox},
                             Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>