#33073: AttributeError when annotating with Exists(none()) and aggregation
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Reporter: Matthijs | Owner: nobody
Kooijman |
Type: | Status: new
Uncategorized |
Component: Database | Version: dev
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I ran into a problem with annotating a field with an Exists subquery,
passing {{{MyModel.objects.none()}}} to Exists. On Django main branch,
this throws an AttributeError, on 2.2.24 this returns an empty queryset
(and printing the query attribute of the queryset raises EmptyResultSet).
Strangely enough this only seems to occur when I add a second annotation
using an aggregation (I tried Sum, Max and Count). Adding a second
aggregation using a plain field (e.g. {{{F('id')}}}) does not seem to
trigger the problem. Each of the annotations individually also work, but
not together.
It seems this already fails on the most basic (empty) model definition, no
options or specific fields required.
I have not really investigated the details, I'm not too familiar with the
query generating code.
Below is a testcase (ready to be included as a regression test).
{{{
--- a/tests/model_regress/tests.py
+++ b/tests/model_regress/tests.py
@@ -236,6 +236,18 @@ class Horse(models.Model, metaclass=HorseBase):
self.assertEqual(Horse.horns, 1)
+ def test_exists_none_with_aggregate(self):
+ Party.objects.create()
+ qs = Party.objects.all().annotate(
+ foo=models.Count('id'),
+ bar=models.Exists(Party.objects.none()),
+ )
+ # Throws EmptyResultSet on 2.2.24, or AttributeError:
'NothingNode' object has no attribute
+ # 'get_source_expressions' on 3.2.6
+ qs.query
+ # Returns empty result on 2.2.24 or throws on 3.2.6
+ self.assertEqual(len(qs), 1)
+
./runtests.py
model_regress.tests.ModelTests.test_exists_none_with_aggregate
(... snip some stuff ...)
Traceback (most recent call last):
File "django/tests/model_regress/tests.py", line 249, in
test_exists_empty_with_aggregate
self.assertEqual(len(qs), 1)
File "django/db/models/query.py", line 262, in __len__
self._fetch_all()
File "django/db/models/query.py", line 1352, in _fetch_all
self._result_cache = list(self._iterable_class(self))
File "django/db/models/query.py", line 51, in __iter__
results = compiler.execute_sql(chunked_fetch=self.chunked_fetch,
chunk_size=self.chunk_size)
File "django/db/models/sql/compiler.py", line 1185, in execute_sql
sql, params = self.as_sql()
File "django/db/models/sql/compiler.py", line 527, in as_sql
extra_select, order_by, group_by = self.pre_sql_setup()
File "django/db/models/sql/compiler.py", line 64, in pre_sql_setup
group_by = self.get_group_by(self.select + extra_select, order_by)
File "django/db/models/sql/compiler.py", line 129, in get_group_by
cols = expr.get_group_by_cols()
File "django/db/models/expressions.py", line 1159, in get_group_by_cols
external_cols = self.get_external_cols()
File "django/db/models/expressions.py", line 1143, in get_external_cols
return self.query.get_external_cols()
File "django/db/models/sql/query.py", line 1057, in get_external_cols
return [
File "django/db/models/sql/query.py", line 1057, in <listcomp>
return [
File "django/db/models/sql/query.py", line 1697, in _gen_cols
expr.get_source_expressions(),
AttributeError: 'NothingNode' object has no attribute
'get_source_expressions'
}}}
(Can be pulled from https://github.com/matthijskooijman/django/blob
/testcase-exists-none/tests/model_regress/tests.py#L239)
--
Ticket URL: <https://code.djangoproject.com/ticket/33073>
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