Is there a good tool for debugging XAML binding behavior / errors at runtime?

Question

WPF is a great toolkit and XAML data binding is very efficient, but I often run into difficulties with its transparency: it can be difficult to debug data binding failure if errors are not thrown.

For example, I recently had to modify a Style declaration as follows:

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

In it:

 <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> 

To affect the DataGridRow property. It would be incredibly useful to see, during design or runtime, what consequences might be associated with different sources and RelativeSource .

Are there any such tools / methods?

Answer 1

You can use the PresentationTraceSources.TraceLevel attached property on bindings to get detailed output logging at 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 need to update the default WPF trace settings .

Answer 3

If you run the application under the Visual Studio debugger, binding errors will be sent to the output window. They are very informative and should help you identify any errors.

Answer 4

Another option in Visual Studio 2010 is to set a breakpoint on the anchor. This can be easily done by placing your click on the Binding keyword and pressing F9 to set a breakpoint. The Binding keyword will be highlighted in red. If a large piece of text is selected, it may be that the breakpoint does not work in the editor you are using. In this case, try right-clicking the file in Solution Explorer, select "Open With" and select "Source Code Editor (text)."

When you hit a breakpoint at runtime, you can test it using the debug locator window and see what it is attached to.