Average messages by hour

0: original_query.sql

SELECT ROUND(AVG(a.posts)) "Posts (avg)", post_hour
FROM (
	SELECT count(id) posts, DATE(post_date) dateonly, EXTRACT(hour FROM post_date) post_hour
	FROM message
	GROUP BY post_hour, dateonly
) a
GROUP BY post_hour
ORDER BY post_hour;

1: (truncated) views.py

def message_average_by_hour(request):
    data = Message.objects.all() \
        .extra(select={'day': connections[Message.objects.db].ops.date_trunc_sql('day', 'post_date')}) \
        .extra({'hour':'extract(hour from post_date)'}) \
        .values('day', 'hour') \
        .annotate(count_items=Count('id'))
    return JsonResponse(list(data), safe=False)

2: (truncated) output.json

[ 
  {"day": "2015-12-19T00:00:00Z", "hour": 21.0, "count_items": 1},
  {"day": "2015-09-14T00:00:00Z", "hour": 13.0, "count_items": 4},
  {"day": "2016-01-26T00:00:00Z", "hour": 21.0, "count_items": 2},
  {"day": "2016-01-25T00:00:00Z", "hour": 6.0, "count_items": 6},
  {"day": "2015-08-21T00:00:00Z", "hour": 10.0, "count_items": 5},
  {"day": "2015-08-25T00:00:00Z", "hour": 13.0, "count_items": 1},
  {"day": "2015-11-20T00:00:00Z", "hour": 10.0, "count_items": 1},
  {"day": "2016-02-02T00:00:00Z", "hour": 7.0, "count_items": 35},
  {"day": "2015-07-17T00:00:00Z", "hour": 6.0, "count_items": 2}
]

3: (desired) output.json

[
  {"hour": 6.0, "average": 4}
  {"hour": 7.0, "average": 35}
  ...
]

3: (truncated) models.py

class Message(models.Model):
    post_date = models.DateTimeField('Date posted')
    username = models.CharField(max_length=50)


    def __str(self):
        return self.username