Demonstration of with_scope for class methods which operate on scoped records

gistfile1.rb

Notification.for_user(user).expire!

Notification.rb

class Notification < ActiveRecord::Base

  belongs_to :user

  scope :for_user, lambda { |user| where(:user_id => user.id) }
  scope :unexpired, where('expired_at is null')

  delf self.expire!
    with_scope do
      # Here we further filter by the `unexpired` scope,
      # but the default scope is available as `scoped`
      # and there is also an `unscoped` method.
      unexpired.each &:expire!
    end
  end
  
  def expire!
    self.expired_at = Time.now
    save!
  end

end