What path should I write in the binding?

Question

I have a WPF app, with a tree view. There's an item template that is hierarchical.

I want to bind an image source to the data class I'm using as TreeViewItem i.e. to RestoreItemVM. What do I need to write in the path??? Everything I tried so far threw an error in my converter saying it's cannot cast it to RestoreItemVM...

<TreeView.ItemTemplate>
    <HierarchicalDataTemplate ItemsSource="{Binding Children}" DataType="restoreTab:RestoreItemVM">
        <DockPanel VerticalAlignment="Center" HorizontalAlignment="Left" LastChildFill="False">
            <CheckBox Focusable="False" VerticalAlignment="Center" IsChecked="{Binding IsChecked}" PreviewMouseRightButtonDown="TreeViewItem_OnPreviewMouseRightButtonDown"/>
            <Image Width="20" Margin="3" 
                   Source="{Binding RelativeSource={RelativeSource 
                            FindAncestor, AncestorType={x:Type TreeViewItem}, 
                            AncestorLevel=2}, Converter={x:Static local:RestoreItemToImageConverter.Instance}, 
                            Path= ????? }"  
                   PreviewMouseRightButtonDown = "TreeViewItem_OnPreviewMouseRightButtonDown"/>
       </DockPanel>
    </HierarchicalDataTemplate>
</TreeView.ItemTemplate>

Answer 1

You need to specify the path to the data context:

Source="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TreeViewItem}}, Converter={x:Static local:RestoreItemToImageConverter.Instance}, 
         Path=DataContext}"

But actually, it's more simple, as RestoreItemVM is already the DataContext of Image as well, you don't need to find it's ancestor. Instead try this:

<Image ... Source="{Binding Path=., Converter={x:Static local:RestoreItemToImageConverter.Instance}}" />

Path=. binds to the DataContext itself:

Special symbols in WPF binding - what does "{Binding Path=.}" mean?

And the DataContext of the DockPanel in the HierarchicalDataTemplate is the current RestoreItemVM object in the ItemsSource.