我正在尝试计算玩家每周玩的次数,如下所示:
player.game_objects.extra(
select={'week': 'WEEK(`games_game`.`date`)'}
).aggregate(count=Count('week'))
但 Django 提示
FieldError: Cannot resolve keyword 'week' into field. Choices are: <lists model fields>
我可以像这样在原始 SQL 中做到这一点
SELECT WEEK(date) as week, COUNT(WEEK(date)) as count FROM games_game
WHERE player_id = 3
GROUP BY week
有没有在 Django 中不执行原始 SQL 的好方法?
最佳答案
您可以使用自定义聚合函数来生成查询:
WEEK_FUNC = 'STRFTIME("%%%%W", %s)' # use 'WEEK(%s)' for mysql
class WeekCountAggregate(models.sql.aggregates.Aggregate):
is_ordinal = True
sql_function = 'WEEK' # unused
sql_template = "COUNT(%s)" % (WEEK_FUNC.replace('%%', '%%%%') % '%(field)s')
class WeekCount(models.aggregates.Aggregate):
name = 'Week'
def add_to_query(self, query, alias, col, source, is_summary):
query.aggregates[alias] = WeekCountAggregate(col, source=source,
is_summary=is_summary, **self.extra)
>>> game_objects.extra(select={'week': WEEK_FUNC % '"games_game"."date"'}).values('week').annotate(count=WeekCount('pk'))
但由于此 API 未记录在案并且已经需要一些原始 SQL,您最好使用 raw query .
关于python - 在 Django 查询中使用 .extra(select={...}) 引入的值上使用 .aggregate()?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4567543/