update.rb

# Data looks like:
# {
#   #"old": new,
#   "7583": 201343,
#   "7614": 280397,
#   "8381": 285146,
#   "9197": 285727,
#   "9356": 220591,
# }

def update_rental_ids(klass, old, new)
  rel = klass.where("rental_id like 'p#{old}-%'")
  rel.each do |thing|
    begin
      new_rid = thing.rental_id.sub("p#{old}-", "p#{new}-")
      new_attrs = {
        rental_id: new_rid,
      }
      new_attrs[:property_id] = new if thing.respond_to?(:property_id)
      puts "Saving #{thing.class.name} #{thing.id}"
      thing.update_attributes!(new_attrs)
    rescue ActiveRecord::RecordNotUnique
      thing.destroy
    end
  end
end

data.each_with_index do |(old, new), i|
  puts "\n\n---#{i}---\n\n"
  [
    Unit,
    UserUnit.includes(:user),
    SavedSearchListing.includes(:saved_searches),
    SpamFlag,
    Community
  ].each do |klass|
    puts "Updating #{klass.name}"
    update_rental_ids(klass, old, new)
  end
end