Is there any way to “group by” by date with Django.models when my MySQL field has hours/min/second as well?

Question

I want to query to MySQL using Django.models, but since I put my created_at (Datetime field) with datetime.datetime.now(), it seems to hard to "group by" with each date. I made a query like this:

start = time.strptime("2012/6/25","%Y/%m/%d")
end = time.strptime("2012/6/26","%Y/%m/%d")
unix_start= time.mktime(start)
unix_end = time.mktime(end)

Mymodels.objects.filter(created_at__range[datetime.datetime.fromtimestamp(unix_start),datetime.datetime.fromtimestamp(unix_end]).values("~~~~~").annotate(player_id=Count("player_id"))

but I guess this query is too heavy for network.Is there any way to "group by" by datetime.date or use (date() for MySQL)in Django.models when my MySQL data is datetime.datetime.now()?

Answer 1

I use PostgreSQL date_trunc() to group values by a date when the dates are saved as Datetime. I think you can use something like this with MySQL:

select_date = {"date": """DATE_FORMAT(start, '%Y-%m-%d')"""}
query = query.extra(select=select_date).values('date')
query = query.annotate(player_id=Count('player_id', distinct=True)).order_by('date')