change rake

lib/tasks/version_v1.rb → lib/tasks/data_migrations/version_v1.rake

@@ -4,12 +4,12 @@ namespace :data_migrations do
     desc "batch delete notification_statistics data"
     task :v1_batch_delete_notification_statistics_data => :environment do
       first_id = NotificationStatistic.first.id
-      last_id = NotificationStatistic.where("notification_statistics.created_at < ?", '2020-04-30 16:00:00').last.id
+      last_object = NotificationStatistic.where("notification_statistics.created_at < ?", '2020-04-30 16:00:00').last
       
       
-      first_id.step(last_id, 10000) do |i|
+      first_id.step(last_object.id, 10000) do |i|
         NotificationStatistic.where(id: [i...i+10000]).delete_all
-      end
+      end if last_object.present?
     end
   end
 end
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