Does ActiveRecord save a belongs_to association when saving main object?

Question

If I have two models:

class Post < ActiveRecord::Base
  belongs_to :user
end

and

class User < ActiveRecord::Base
  has_many :posts
end

If I do:

post = Post.new
user = User.new
post.user = user
post.save

Does the user get saved as well and the primary key properly assigned in post's user_id field?

Answer 1

ActiveRecord belong_to assosications has the ability to be autosaved along with the parent model, but the functionality is off by default. To enable it:

class Post < ActiveRecord::Base
  belongs_to :user, :autosave => true
end