Wpf – Can you bind a DataTrigger to an Attached Property

bindingdatatriggerwpf

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).

Best Answer

You need to wrap the property in parentheses:

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