keeping 2 model records in sync - callbacks infinite loop

Question

I have 2 records of the same model, and I want to keep some of the data on these records in sync.

I was going to do a after_save callback (or maybe observer) to trigger updating the other record, but I am afraid this is going to cause an infinite loop of saves because the other record will cause a callback.

I read here that you can bypass callbacks on save, but these approaches seem to be hackish and not consistent between rails 2 and 3 (we are moving to rails 3 in a couple months).

Is there a better option?

Answer 1

You can use the update_columns method while updating the 2nd record based on updates on the first one and vice versa.

Answer 2

You can create attr_accessor:

attr_accessor :dont_run_callback

after_save :my_callback

def my_callback
  MyModel.find(1).update_attributes(..., :dont_run_callback => true)  unless dont_run_callback
end

something like that