Aggregate

Import

from django.db.models import Avg, Max, Min, Count, Sum

Sample

From Generating aggregates over a QuerySet:

>>> from django.db.models import Avg
>>> Book.objects.aggregate(Avg('price'))
{'price__avg': 34.35}

>>> from django.db.models import Avg, Max, Min, Count
>>> Book.objects.aggregate(Avg('price'), Max('price'), Min('price'))
{'price__avg': 34.35, 'price__max': Decimal('81.20'), 'price__min': Decimal('12.99')}

Note: The aggregate method returns a dictionary. To specify the key name:

>>> Book.objects.aggregate(average_price=Avg('price'))
{'average_price': 34.35}

From Aggregations and other QuerySet clauses:

Book.objects.annotate(num_authors=Count('authors')).filter(num_authors__gt=1)

village_rows = Villages.objects.filter(
    voting__completed__isnull=True
).annotate(
    voter_count=Count('voting')
).filter(
    voter_count__gt=300
)

q = Post.objects.annotate(Max('comment'))
q[0]
q[0].comment__max
q[2].id
q[2].comment__max

Group

village_rows = Villages.objects.filter(
    voting__completed__isnull=True
).values(
    'category__name'
).annotate(
    voter_count=Count('pk')
)