Fix rating (DMOJ)

judge/ratings.py

@@ -2,7 +2,7 @@ import math
 from bisect import bisect
 from operator import attrgetter, itemgetter
 
-from django.db import connection, transaction
+from django.db import transaction
 from django.db.models import Count, OuterRef, Subquery
 from django.db.models.functions import Coalesce
 from django.utils import timezone
@@ -152,18 +152,12 @@ def rate_contest(contest):
     now = timezone.now()
     ratings = [Rating(user_id=i, contest=contest, rating=r, volatility=v, last_rated=now, participation_id=p, rank=z)
                for i, p, r, v, z in zip(user_ids, participation_ids, rating, volatility, ranking)]
-    cursor = connection.cursor()
-    cursor.execute('CREATE TEMPORARY TABLE _profile_rating_update(id integer, rating integer)')
-    cursor.executemany('INSERT INTO _profile_rating_update VALUES (%s, %s)', list(zip(user_ids, rating)))
     with transaction.atomic():
         Rating.objects.filter(contest=contest).delete()
         Rating.objects.bulk_create(ratings)
-        cursor.execute('''
-            UPDATE `%s` p INNER JOIN `_profile_rating_update` tmp ON (p.id = tmp.id)
-            SET p.rating = tmp.rating
-        ''' % Profile._meta.db_table)
-    cursor.execute('DROP TABLE _profile_rating_update')
-    cursor.close()
+        Profile.objects.filter(contest_history__contest=contest, contest_history__virtual=0) \
+                       .update(rating=Subquery(Rating.objects.filter(user=OuterRef('id')) \
+                       .order_by('-contest__end_time').values('rating')[:1]))
     return old_rating, old_volatility, ranking, times_ranked, rating, volatility