Question

I’ve just started testing the water with WPF and I’m trying to bind the expanded property of an expander and the selected property of a listview item together so that when a list view item is selected the expander expands or going down another road trying to set the listview item to selected on expand of the expander

so far I’ve got

<ListView HorizontalAlignment="Stretch"  Name="listView1" VerticalAlignment="Stretch" SelectionMode="Single" >
        <ListView.Resources>
            <Style TargetType="{x:Type ListViewItem}">
                <Setter Property="IsSelected" Value="{Binding Path=IsExpanded, Mode=TwoWay}"/>
            </Style>
        </ListView.Resources>
        <ListView.ItemTemplate>
            <DataTemplate>
                <Expander>
                        <TextBlock Text="{Binding Name}"></TextBlock>
                </Expander>
            </DataTemplate>
        </ListView.ItemTemplate>            
    </ListView>

But I can’t figure out how to reference the expander in the binding. Any help or a nudge in the right direction would be appreciated.

Thanks

Answer 1

Well..

You can not connect listboxitem with its own template … Because basically they do not know… That would not work here:

 <Style TargetType="ListBoxItem">
             <Style.Triggers>
                    <DataTrigger Binding="{Binding ElementName=expanderHeader,Mode=OneWay}" Value="True">
                 <Setter Property="IsSelected" value="True"/>
                    </ DataTrigger>
             </ Style.Triggers>
     </ Style>

You also can not fire a trigger of the expander, because setters do not accept binding ..
  

<Expander.Style>
     <Style TargetType="Expander">
         <Style.Triggers>
             <Trigger Property="IsExpanded" Value="True">
                 <Setter Property="{Binding RelativeSource={RelativeSource AncestorType=ListBoxItem, Mode=FindAncestor}, Path=IsSelected}" Value="True"/>
             </ Trigger>
          </ Style.Triggers>
     </ Style>
</ Expander.Style>

The answer is this:

    <ListBox.ItemTemplate>
        <DataTemplate>
               <Expander  x:Name="expanderHeader" IsExpanded="{Binding Mode=TwoWay, Path=IsSelected, RelativeSource={RelativeSource AncestorType=ListBoxItem, Mode=FindAncestor}}">
                 <!-- Content -->
                </Expander>
        </DataTemplate>
    </ListBox.ItemTemplate>

If you prefer you can use the binding, mode = OneWayToSource, depending on your needs ..