Question

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 1

You need to wrap the property in parentheses:

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