Is there a good tool for debugging XAML's databinding behavior / errors at runtime?

Question

WPF is a great toolset, and XAML databinding is very powerful, but I've often run into difficulty arising from its transparency: It can be tough to debug a databinding failure when no errors are thrown.

For example, I recently had to change a Style declaration like this:

<DataGrid.RowStyle>     <Style>         <Style.Triggers>             <DataTrigger Binding="{Binding TestProperty}" Value="False">                 <Setter Property="DataGridRow.Background" Value="Red"/>             </DataTrigger>         </Style.Triggers>     </Style> </DataGrid.RowStyle> 

Into this:

<DataGrid.RowStyle>     <Style>         <Style.Triggers>             <DataTrigger Binding="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.TestProperty}" Value="False">                 <Setter Property="DataGridRow.Background" Value="Red"/>             </DataTrigger>         </Style.Triggers>     </Style> </DataGrid.RowStyle> 

In order for the DataGridRow property to be affected. It would be incredibly helpful to see, at design- or run-time, what the implications of binding to different sources and RelativeSources would be.

Do any such tools / techniques exist?

Answer 1

You can use PresentationTraceSources.TraceLevel attached property on bindings to get detailed logging in the output during runtime.

In your case, it will look like this:

<DataGrid.RowStyle>     <Style>         <Style.Triggers>             <DataTrigger Value="False" Binding="{Binding DataContext.TestProperty,                     RelativeSource={RelativeSource AncestorType=UserControl},                     PresentationTraceSources.TraceLevel=High}">                 <Setter Property="DataGridRow.Background" Value="Red"/>             </DataTrigger>         </Style.Triggers>     </Style> </DataGrid.RowStyle> 

Answer 2

Bea Stollnitz has a very informative blog post about debugging WPF bindings.

If you are using Visual Studio 2010, you will need to update the default WPF trace setting.