Rails - Jun 2006 - Refreshing remote :through associations with deletes

Hi everyone,

I''m refreshing the local Rails database from a remote database every
10 minutes.  I''m using a :through association to relate people to
mailinglists through subscriptions.

# Works fine, every 10 minutes:
remote_lists.each { |list| List.find_or_create_by_name(list.name) }
remote_subscribers.each do |subscriber|
  person = Person.find_by_email(subscriber.user)
  unless person.nil?
    Subscription.find_or_create_by_person_id_and_mailinglist_id(person.id,
local_list.id)
  end
end

remote_lists.each do |list|
  local_list = Mailinglist.find_or_create_by_name(list.list)
  subscribers
MailinglistSubscriptionRemote.find_all_by_list_subscriber(local_list.name)
  if subscribers.size > 0
    subscribers.each do |subscriber|
      person = Person.find_by_email(subscriber.user)
      unless person.nil?
        Subscription.find_or_create_by_person_id_and_mailinglist_id(person.id,
local_list.id)
      end
    end
  end
end

What I need to do is make sure that if blah@blah.com unsubscribes from
a list, the associated Subscription is removed.  I know I''m not
accounting for that here.  How should I do that?

Thanks!

Sean