Can you bind a DataTrigger to an Attached Property?

wpf binding datatrigger
Brad Leach picture Brad Leach · Sep 10, 2008 · Viewed 7.8k times · Source

In WPF, is it possible for a DataTrigger to bind to an attached property?

I essentially want to use a converter on an attached property to provide a style when a particular validation rule has been broken. I am using markup like the following:

<DataTrigger Binding="{Binding Path=Validation.Errors, 
                       RelativeSource={RelativeSource Self}, 
                       Converter={StaticResource RequiredToBoolConverter}}" 
                       Value="True">
  <Setter Property="Background" Value="LightGreen" />
</DataTrigger>

However, when this runs, I get the following:

System.Windows.Data Error: 39 : BindingExpression path error: 'Validation' property not found on 'object' ''TextBox' (Name='')'. BindingExpression:Path=Validation.Errors; DataItem='TextBox' (Name=''); target element is 'TextBox' (Name=''); target property is 'NoTarget' (type 'Object')

If I change my DataTrigger binding path to "Text", I do not get the databinding error (but of course it does not provide the behaviour I am seeking).

Answer

Kent Boogaart picture Kent Boogaart · Sep 10, 2008

You need to wrap the property in parentheses:

<DataTrigger Binding="{Binding Path=(Validation.Errors).YourAttachedProperty,...

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