From 6294baf4568b9beaf14fd3907da1ea02f79ebc54 Mon Sep 17 00:00:00 2001
From: bmedx <bmesick@edx.org>
Date: Wed, 6 Dec 2017 12:48:05 -0500
Subject: [PATCH] Add command to bulk move user language prefs from one code to
 another

---
 .../commands/migrate_user_profile_langs.py    | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 openedx/core/djangoapps/user_api/management/commands/migrate_user_profile_langs.py

diff --git a/openedx/core/djangoapps/user_api/management/commands/migrate_user_profile_langs.py b/openedx/core/djangoapps/user_api/management/commands/migrate_user_profile_langs.py
new file mode 100644
index 0000000000..c8a064d351
--- /dev/null
+++ b/openedx/core/djangoapps/user_api/management/commands/migrate_user_profile_langs.py
@@ -0,0 +1,101 @@
+"""
+Migrates user preferences from one language code to another in batches. Dark lang preferences are not affected.
+"""
+from __future__ import print_function
+
+import logging
+from time import sleep
+
+from django.conf import settings
+from django.core.management.base import BaseCommand, CommandError
+from django.db import transaction
+from django.db.models import Q, Max
+
+from openedx.core.djangoapps.dark_lang.models import DarkLangConfig
+from openedx.core.djangoapps.user_api.models import UserPreference
+
+
+DEFAULT_CHUNK_SIZE = 10000
+DEFAULT_SLEEP_TIME_SECS = 10
+
+LOGGER = logging.getLogger(__name__)
+
+
+class Command(BaseCommand):
+    """
+    Implementation of the migrate command
+    """
+    help = 'Migrate all user language preferences (excluding dark languages) from one language code to another.'
+
+    def add_arguments(self, parser):
+        parser.add_argument('old_lang_code',
+                            help='Original language code, ex. "zh-cn"')
+        parser.add_argument('new_lang_code',
+                            help='New language code, ex. "zh-hans"')
+        parser.add_argument('--start_id',
+                            type=int,
+                            default=1,
+                            help='ID to begin from, in case a run needs to be restarted from the middle.')
+        parser.add_argument('--chunk_size',
+                            type=int,
+                            default=DEFAULT_CHUNK_SIZE,
+                            help='Number of users whose preferences will be updated per batch.')
+        parser.add_argument('--sleep_time_secs',
+                            type=int,
+                            default=DEFAULT_SLEEP_TIME_SECS,
+                            help='Number of seconds to sleep between batches.')
+
+    def handle(self, *args, **options):
+        """
+        Execute the command.
+        """
+        old_lang_code = options['old_lang_code']
+        new_lang_code = options['new_lang_code']
+        chunk_size = options['chunk_size']
+        sleep_time_secs = options['sleep_time_secs']
+        start = options['start_id']
+        end = start + chunk_size
+
+        # Make sure we're changing to a code that actually exists. Presumably it's safe to move away from a code that
+        # doesn't.
+        langs = [lang_code[0] for lang_code in settings.LANGUAGES]
+        langs += DarkLangConfig.current().released_languages_list
+
+        if new_lang_code not in langs:
+            raise CommandError('{} is not a configured language code in settings.LANGUAGES '
+                               'or the current DarkLangConfig.'.format(new_lang_code))
+
+        max_id = UserPreference.objects.all().aggregate(Max('id'))['id__max']
+
+        print('Updating user language preferences from {} to {}. '
+              'Start id is {}, current max id is {}. '
+              'Chunk size is of {}'.format(old_lang_code, new_lang_code, start, max_id, chunk_size))
+
+        updated_count = 0
+
+        while True:
+            # On the last time through catch any new rows added since this run began
+            if end >= max_id:
+                print('Last round, includes all new rows added since this run started.')
+                id_query = Q(id__gte=start)
+            else:
+                id_query = Q(id__gte=start) & Q(id__lt=end)
+
+            curr = UserPreference.objects.filter(
+                id_query,
+                key='pref-lang',
+                value=old_lang_code
+            ).update(value=new_lang_code)
+
+            updated_count += curr
+
+            print('Updated rows {} to {}, {} rows affected'.format(start, end - 1, curr))
+
+            if end >= max_id:
+                break
+
+            start = end
+            end += chunk_size
+            sleep(sleep_time_secs)
+
+        print('Finished! Updated {} total preferences from {} to {}'.format(updated_count, old_lang_code, new_lang_code))