Rails3 - Adding default values to associated table after_create

I'am looking for a way to add intiatlize an associated DB after the parent is created.

I have a simple User model with just the filed username and a related (has_many) child Place model with the field placenames.

After the user was created succsefully, the table of Places should be filled with entry's like: europe, asia, afrika. I think the way to go is to use the after_create method but i can't find how to trigger the creation from my parent model.

You can declare the after_create like this

class User 

  after_create :initialize_places

  def initialize_places
    self.places.create(:placename => 'Europe')
    self.places.create(:placename => 'Asia')
    self.places.create(:placename => 'Africa')
  end
end

And create the user like this

user = User.create(:username => 'The Black Adder')