def with_advice_status(self):
return self.annotate(advice_count=Count("advice")).annotate(
has_advice=expressions.Case(
expressions.When(advice_count=0, then=False),
default=True,
output_field=BooleanField(),
))
def IsNotNone(*fields, default=None):
"""Selects whichever field is not None, in the specified order.
Arguments:
fields:
The fields to attempt to get a value from,
in order.
default:
The value to return in case all values are None.
Returns:
A Case-When expression that tries each field and
returns the specified default value when all of
them are None.
"""
when_clauses = [
expressions.When(~expressions.Q(**{field: None}),
then=expressions.F(field))
for field in reversed(fields)
]
return expressions.Case(
*when_clauses,
default=expressions.Value(default),
output_field=CharField(),
)
def get_queryset(self) -> models.QuerySet:
qs = self.queryset.annotate(has_user=expressions.Case(
expressions.When(
user__isnull=False,
then=expressions.Value(True),
),
default=expressions.Value(False),
#
# Tell Django the expected type of the field, see `output_field` in
# https://docs.djangoproject.com/en/2.1/ref/models/expressions/
#
output_field=models.BooleanField()))
logger.info(qs.query)
return qs
