New model object through an association

Question

I thought it was possible to create a new model object through an association.

class Order < ActiveRecord::Base
  belongs_to :basket
end

class Basket < ActiveRecord::Base
  has_one :order
end

order = Order.new()
basket = order.basket.new() # NoMethodError: undefined method `new' for nil:NilClass

Solution

It is, but your syntax is a little wrong:

class Order < ActiveRecord::Base
  belongs_to :basket
end

class Basket < ActiveRecord::Base
  has_one :order
end

order = Order.new()
basket = order.create_basket()

Use build_basket if you don't want to save the basket immediately; if the relationship is has_many :baskets instead, use order.baskets.create() and order.baskets.build()

Comments

[pingu]

Thanks Chris for your reply, out of interest i tried basket = order.basket.new() when the relationship is has_many :baskets, and it worked fine. Its all very confusing.

[gertas]

It may work, but I'm not sure if order.basket collection will contain your newly created object, which means you can save order and have all child objects autosaved and referenced to order (without specifying it in parameters).