validates_associated :customer
validates_associated :rentable
+ def overdue?
+ return due_date < Time.now.to_date
+ end
+
+ def late_fee
+ days_late = Time.now.to_date - (due_date)
+ return VideoPolicy.find_by_day(8).fee * days_late.to_i
+ end
+
protected
def validate
errors.add(:customer_id, "does not exist is the database") if customer.nil?