Make sure enterprises have a valid address after pickup address field has been removed

db/migrate/20121028070200_remove_pickup_address_from_enterprises.rb

@@ -1,5 +1,21 @@
 class RemovePickupAddressFromEnterprises < ActiveRecord::Migration
-  def change
+  class Enterprise < ActiveRecord::Base; end
+
+  def up
+    Enterprise.all.each do |e|
+      e.address_id ||= e.pickup_address_id
+      e.save!
+    end
+
     remove_column :enterprises, :pickup_address_id
   end
+
+  def down
+    add_column :enterprises, :pickup_address_id, :integer
+
+    Enterprise.all.each do |e|
+      e.pickup_address_id ||= e.address_id
+      e.save!
+    end
+  end
 end