Question

I’m trying to set one of two Bindings on a ListBox‘s ItemsSource (based on the selection in a group of RadioButtons).

What I have now is:

<ListBox>
    <ListBox.Resources>
        <Binding x:Key="AllBinding" Path="ItemsSource.AllLeaves" ElementName="EmployeeTree" />
        <Binding x:Key="FolderBinding" Path="SelectedItem.Leaves" ElementName="EmployeeTree" />
    </ListBox.Resources>
</ListBox>

Then ideally I would set one or the other to the ItemsSource based on the user’s selection.

But I get this error on both Bindings:

A ‘Binding’ cannot be set on the ‘Value’ property of type ‘DictionaryEntry’. A ‘Binding’ can only be set on a DependencyProperty of a DependencyObject.

How can I implement this requirement? Is it even possible to define the Bindings so I can just swap them in and out from code behind?

Answer 1

It sounds like you are trying to set your TreeView.ItemsSource based on the selected item in some ListBox.

If this is the case, you should write a DataTrigger on your EmployeeTree that sets TreeView.ItemsSource based on the ListBox.SelectedItem or ListBox.SelectedIndex

<Style x:Key="EmployeeTreeStyle" TargetType="{x:Type TreeView}">
    <!-- By default bind to MyListBox.SelectedItem.Leaves -->
    <Setter Property="ItemsSource" Value="{Binding ElementName=MyListBox, Path=SelectedItem.Leaves}" />
    <Style.Triggers>
        <!-- If SelectedIndex = 0, bind to AllLeaves instead -->
        <DataTrigger Binding="{Binding ElementName=MyListBox, Path=SelectedIndex}" Value="0">
            <Setter Property="ItemsSource" Value="{Binding AllLeaves}" />
        </DataTrigger>
    </Style.Triggers>
</Style>

Update based on comments below

<Style x:Key="EmployeeTreeStyle" TargetType="{x:Type TreeView}">
    <Style.Triggers>
        <!-- Set ItemsSource based on which RadioButton is Selected -->
        <DataTrigger Binding="{Binding ElementName=RadioButton1, Path=IsChecked}" Value="True">
            <Setter Property="ItemsSource" Value="{Binding AllLeaves}" />
        </DataTrigger>
        <DataTrigger Binding="{Binding ElementName=RadioButton2, Path=IsChecked}" Value="True">
            <Setter Property="ItemsSource" Value="{Binding ElementName=RadioButton2, Path=DataContext.Leaves}" />
        </DataTrigger>
    </Style.Triggers>
</Style>