Why attached property Set and Get static methods are not called in XAML?

Question

Hi,

I have set break points on my attached properties SetXXX and GetXXX static methods. In Xaml, I have assigned values to the attached property. However, I was expecting the Set or Get static methods to be called but they are not. The attached property works as expected and if I call SetXXX and GetXXX methods in code, then it works are expected.

Why are the methods not called when set from Xaml?

JD.

Answer 1

XAML does not understand normal property getter and setters when it comes to attached properties. Instead it goes straight to the lower level APIs on DependencyObject. Namely the GetValue and SetValue methods.

Answer 2

As JaredPar explained, when you use XAML, the GetXXX/SetXXX methods are not called.

I wanted to add something, though:

If you need to track changes to the Attached Property in code, you should use the Metadata. You can set a callback in the metadata to fire when the property changes, and track it in your code.