ruby - Rails 4.2: has_many using condition from belongs

i have 3 activerecords. order, has_many orderitems. has field named status. orderitem, belongs_to order , script script, has_many orderitems

i want set has_many in script model orderitems belong order has status of 'paid' given.

i'm new rails, , isn't codebase i'm struggling bit. i've seen other answers use :include , :conditions keywords, neither valid in rails 4.2

any great.

i try keeping things bit pure ensuring models not involved in defining how other models behave.

start defining scope order define mean "paid".

def self.has_been_paid   where(status: "paid") end

then can associate orderitems paid order.

belongs_to :paid_order, -> {merge(order.has_been_paid)}, :class_name => "order", :foreign_key => :order_id

... , scope ...

def self.for_paid_orders   joins(:paid_order) end

then script:

has_many :order_items, -> {merge(orderitem.for_paid_orders)}

so each model takes care of own business.

Braziel