Count number of records by date in Django

This should work (using the same MySQL specific function you used):

Review.objects.filter(venue__pk=2)
    .extra({'date_created' : "date(datetime_created)"})
    .values('date_created')
    .annotate(created_count=Count('id'))

Now that Extra() is being depreciated a more appropriate answer would use Trunc such as this accepted answer

Now the OP's question would be answered as follows

from django.db.models.functions import TruncDay

Review.objects.all()
    .annotate(date=TruncDay('datetime_created'))
    .values("date")
    .annotate(created_count=Count('id'))
    .order_by("-date")

Just for completeness, since extra() is aimed for deprecation, one could use this approach:

from django.db.models.expressions import DateTime

Review.objects.all().\
    annotate(month=DateTime("timestamp", "month", pytz.timezone("Etc/UTC"))).\
    values("month").\
    annotate(created_count=Count('id')).\
    order_by("-month")

It worked for me in django 1.8, both in sqlite and MySql databases.

If you were storing a date field, you could use this:

from django.db.models import Count

Review.objects.filter(venue__pk = 2)
    .values('date').annotate(event_count = Count('id'))

Because you're storing datetime, it's a little more complicated, but this should offer a good starting point. Check out the aggregation docs here.