ActiveRecord `has_one` association extension method

Question

I've tried to extend has_one association with method:

has_one :subscription_plan, -> { where current: true } do
  def in newspaper
    where newspaper: newspaper
  end
end

and got an error undefined method 'in' for #<SubscriptionPlan...>

But it works with has_many :

has_many :subscription_plans, -> { where current: true } do
  def in newspaper
    where(newspaper: newspaper).take
  end
end

How to make it works with has_one on Rails 4.2.1?

Answer 1

By accessing has_many association you receive SubscriptionPlan::ActiveRecord_Associations_CollectionProxy but with has_one you simply receive SubscriptionPlan instance itself.

So there is nothing here to be extended.

If you would provide more information about your models I would help you with exact code.