How to convert records including 'include' associations to JSON

If I do something like:

result =  Appointment.find( :all, :include => :staff )
logger.debug { result.inspect }

then it only prints out the Appointment data, and not the associated staff data. If I do result[0].staff.inpsect then I get the staff data of course.

The problem is I want to return this to AJAX as JSON, including the staff rows. How do I force it to include the staff rows, or do I have to loop through and create something manually?