Question

I have a Printer model to which I added a master boolean column. A printer belongs_to :restaurant. The master flag indicated whether this printer is the primary printer of this restaurant.

I have a method in the Printer model:

def set_master_on_create
  if self.restaurant.printers.empty?
    self[:master] = true
  else
    self[:master] = false
  end
end

and set this callback: before_create :set_master_on_create

If I run this method as a before_create then creating a new printer will fail. If I change the callback to after_validation creating the new object will work flawlessly, even with the :on => :create option.

Does Rails freeze the object so i can no longer change values after a certain point which will cause the Rollback I get? Any help appreciated.

I am on Rails 3.2.2 and sqlite in dev mode.

Answer 1

i think the problem is that a before_create method returning false will prevent your object from being saved. try adding a return true

and i guess you set the master attribute like this: self.master = true

def set_master_on_create
  if self.restaurant.printers.empty?
    self.master = true
  else
    self.master = false
  end

  return true
end

If a before_* callback cancels the action a ROLLBACK is issued. You
can also trigger a ROLLBACK raising an exception in any of the
callbacks, including after_* hooks. Note, however, that in that case
the client needs to be aware of it because an ordinary save will raise
such exception instead of quietly returning false.
http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html