Django filter by number of ForeignKey and less than a month in DateField -

i have model this:

class moviehistory(models.model):     watched_by = models.foreignkey(user)     time = models.datetimefield(auto_now_add=true)     movie = models.foreignkey(movie) 

i want 15 movies watched in last 30 days. far have this:

movie.objects.filter(time__gte=datetime.now()-timedelta(days=30))

how filter again, , order them movie count? know can filter first 15 results this: [:15], don't know how order amount of movies in model, , pick 1 of each (so don't have repeated moviehistories same movies on each one).

thanks.

annotation best approach:

from django.db.models import count most_watched = movie.objects.all().annotate(num_watched = count('watched_by')).order_by('-num_watched')[:15] 

i haven't tested this, believe on way answer. please let me know if works! may need replace count('watched_by') count('watched_by_id') or whatever field name in database (check ./manage.py sql your_appname).

hope helps!

for more on using these annotations: https://docs.djangoproject.com/en/dev/topics/db/aggregation/#cheat-sheet