[Django] #34975: Getting refs is not work properly with models.Window and aggregation

[Django]

#34975: Getting refs is not work properly with models.Window and aggregation
-------------------------------------+-------------------------------------
Reporter: Zwergpro | Owner: nobody
Type: Bug | Status: new
Component: Database | Version: 4.2
layer (models, ORM) | Keywords: QuerySet, Window,
Severity: Normal | Aggregate, F
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I found out that getting refs in QuerySet doesn't work with models.Window
when I try to use aggregate method. It happened when I tried to update
Django to 4.2.7.

For example:
{{{
MyModel.objects.annotate(
new_ordering=Window(RowNumber(), order_by=[F('ordering')])
).aggregate(
wrong_count=Count('id', filter=Q(ordering=F('new_ordering')))
)
}}}

And as a result, it fails with:
{{{
Traceback (most recent call last):
File "/main.py", line 38, in <module>
result = ordering_query.aggregate(
File "/python3.10/site-packages/django/db/models/query.py", line 592, in
aggregate
return self.query.chain().get_aggregation(self.db, kwargs)
File "/python3.10/site-packages/django/db/models/sql/query.py", line
398, in get_aggregation
aggregate = aggregate_expr.resolve_expression(
File "/python3.10/site-packages/django/db/models/aggregates.py", line
70, in resolve_expression
for ref in c.get_refs():
File "/python3.10/site-packages/django/db/models/expressions.py", line
418, in get_refs
refs |= expr.get_refs()
File "/python3.10/site-packages/django/db/models/sql/where.py", line
233, in get_refs
refs |= child.get_refs()
File "/python3.10/site-packages/django/db/models/expressions.py", line
418, in get_refs
refs |= expr.get_refs()
File "/python3.10/site-packages/django/db/models/expressions.py", line
418, in get_refs
refs |= expr.get_refs()
AttributeError: 'NoneType' object has no attribute 'get_refs'
}}}

It happens because of Window.get_source_expressions return:
{{{
def get_source_expressions(self):
return [self.source_expression, self.partition_by, self.order_by,
self.frame]
}}}
and if we don't specify 'frame' (for example) it will be None in the list.

And in models.aggregates.Aggregate.resolve_expression when we try to find
all refs
https://github.com/django/django/blob/47f9b8dca16b1fdc054b338d81eb080eabad0edf/django/db/models/aggregates.py#L70C30-L70C30
it fails because of we have None in Window.get_source_expressions
{{{
def get_refs(self):
refs = set()
for expr in self.get_source_expressions():
refs |= expr.get_refs()
return refs
}}}

--
Ticket URL: <https://code.djangoproject.com/ticket/34975>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

[Django]

#34975: Getting refs is not work properly with models.Window and aggregation
-------------------------------------+-------------------------------------
Reporter: Zwergpro | Owner: nobody
Type: Bug | Status: new

Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: QuerySet, Window, | Triage Stage:
Aggregate, F | Unreviewed
Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Description changed by Zwergpro:

Old description:

New description:

I found out that getting refs in QuerySet doesn't work with models.Window
when I try to use aggregate method. It happened when I tried to update
Django to 4.2.7.

For example:
{{{
MyModel.objects.annotate(
new_ordering=Window(RowNumber(), order_by=[F('ordering')])
).aggregate(

new_count=Count('id', filter=Q(ordering=F('new_ordering')))
)
}}}

--

--
Ticket URL: <https://code.djangoproject.com/ticket/34975#comment:1>