from django.db.models import Aggregate
class Sum(Aggregate):
# Supports SUM(ALL field).
function = 'SUM'
template = '%(function)s(%(all_values)s%(expressions)s)'
allow_distinct = False
def __init__(self, expression, all_values=False, **extra):
super().__init__(
expression,
all_values='ALL ' if all_values else '',
**extra
)