In a class-based view, all of the elements from the URL are placed into self.args (if they’re non-named groups) or self.kwargs (for named groups). So, for your view, you can use self.kwargs['pk'].
In a class-based view, all of the elements from the URL are placed into self.args (if they’re non-named groups) or self.kwargs (for named groups). So, for your view, you can use self.kwargs['pk'].