#30462: Aggregation with annotation(Subquery) throws AssertionError:
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
rhals000327 |
Type: | Status: new
Uncategorized |
Component: Database | Version: 2.2
layer (models, ORM) | Keywords: aggregation,
Severity: Normal | annotation, subquery
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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Aggregating+Count works fine when filtering argument exists in model.
BUT if it doesn't exist in model it throws an AssertionError.
I'll make an reproducible case below.
models.py
{{{
class Highlight(models.Model):
class Meta:
managed = False
db_table = 'test_highlight'
content = models.CharField(max_length=100)
lang = models.IntegerField(null=True, blank=True)
class Page(models.Model):
class Meta:
managed = False
db_table = 'test_Page'
image = models.CharField(max_length=100)
index = models.IntegerField()
image_size = models.FloatField(default=1)
text_id = models.PositiveIntegerField(blank=True, null=True,
help_text='Includes Highlight ID')
class Ebook(models.Model):
class Meta:
managed = False
db_table = 'test_Book'
title = models.CharField(max_length=100)
page = models.ForeignKey(Page, related_name='book')
class Company(models.Model):
class Meta:
managed = False
db_table = 'test_company'
name = models.CharField(max_length=100)
books = models.ManyToManyField(EBook, related_name='company')
type = models.PositiveIntegerField(blank=True, null=True)
}}}
Our Mission is to get count of Specific Highlight Language Counts.
And below is query for it
{{{
Company.objects.annotate(lang=Subquery(Highlight.objects.filter(pk=OuterRef('books__page__text_id')).values('lang')).values('lang').filter(lang__isnull=False,
lang__in=[1,2,3]).aggregate(highlight_count=Count('pk', distinct=True,
filter=Q(lang=1))
}}}
:::Expected behaviour:::
A dictionary is returned: {'hightlight_count': <value>}, containing value
the number where Highlight_lang is 1.
:::Actual behaviour:::
Returns Assertion Error in query. No Exception Message is supplied for the
error.
Making a similiar query not using annotated field works like
{{{
Company.objects.annotate(lang=Subquery(Highlight.objects.filter(pk=OuterRef('books__page__text_id')).values('lang')).values('lang').filter(lang__isnull=False,
lang__in=[1,2,3]).aggregate(page_count=Count('pk', distinct=True,
filter=Q(type__isnull=False, type=3))
}}}
----
Stacktrace
{{{
~/{{ path }}lib/python3.7/site-packages/django/db/models/query.py in
aggregate(self, *args, **kwargs)
377 if not query.annotations[alias].contains_aggregate:
378 raise TypeError("%s is not an aggregate
expression" % alias)
--> 379 return query.get_aggregation(self.db, kwargs)
380
381 def count(self):
~/{{ path }}lib/python3.7/site-packages/django/db/models/sql/query.py in
get_aggregation(self, using, added_aggregate_names)
459 for alias, expression in
list(inner_query.annotation_select.items()):
460 if expression.is_summary:
--> 461 expression, col_cnt =
inner_query.rewrite_cols(expression, col_cnt)
462 outer_query.annotations[alias] =
expression.relabeled_clone(relabels)
463 del inner_query.annotations[alias]
~/{{ path }}lib/python3.7/site-packages/django/db/models/sql/query.py in
rewrite_cols(self, annotation, col_cnt)
389 # copied from the else clause, but this condition
must appear
390 # before the contains_aggregate/is_summary
condition below.
--> 391 new_expr, col_cnt = self.rewrite_cols(expr,
col_cnt)
392 new_exprs.append(new_expr)
393 elif isinstance(expr, Col) or (expr.contains_aggregate
and not expr.is_summary):
~/{{ path }}lib/python3.7/site-packages/django/db/models/sql/query.py in
rewrite_cols(self, annotation, col_cnt)
389 # copied from the else clause, but this condition
must appear
390 # before the contains_aggregate/is_summary
condition below.
--> 391 new_expr, col_cnt = self.rewrite_cols(expr,
col_cnt)
392 new_exprs.append(new_expr)
393 elif isinstance(expr, Col) or (expr.contains_aggregate
and not expr.is_summary):
~/{{ path }}lib/python3.7/site-packages/django/db/models/sql/query.py in
rewrite_cols(self, annotation, col_cnt)
402 # Some other expression not referencing database
values
403 # directly. Its subexpression might contain Cols.
--> 404 new_expr, col_cnt = self.rewrite_cols(expr,
col_cnt)
405 new_exprs.append(new_expr)
406 annotation.set_source_expressions(new_exprs)
~/{{ path }}lib/python3.7/site-packages/django/db/models/sql/query.py in
rewrite_cols(self, annotation, col_cnt)
404 new_expr, col_cnt = self.rewrite_cols(expr,
col_cnt)
405 new_exprs.append(new_expr)
--> 406 annotation.set_source_expressions(new_exprs)
407 return annotation, col_cnt
408
~/{{ path }}lib/python3.7/site-packages/django/db/models/expressions.py in
set_source_expressions(self, exprs)
172
173 def set_source_expressions(self, exprs):
--> 174 assert not exprs
175
176 def _parse_expressions(self, *expressions):
AssertionError:
}}}
Tested with three django versions. - 2.2.1 / 2.2 / 2.1
None of those worked
Python - 3.7.5
--
Ticket URL: <https://code.djangoproject.com/ticket/30462>
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