#29810: Left outer join using FilteredRelation failed on empty result
-------------------------------------+-------------------------------------
Reporter: Dmitrii Azarenko | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 2.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: ORM | Triage Stage:
FilteredRelation | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Dmitrii Azarenko:
Old description:
> When I try to join table with using `FilteredRelation` clause it failed
> if the result of a joined table is null.
> This error can be reproduce by adding the following test case to the
> corresponding
> [https://github.com/django/django/blob/2.0/tests/filtered_relation/tests.py#L9
> test module]:
> {{{#!div style="font-size: 80%"
> tests.filtered_relation.tests.FilteredRelationTests:
> {{{#!python
> def test_select_related_empty_join(self):
> self.assertFalse(
> Author.objects.annotate(
> empty_join=FilteredRelation('book', condition=Q(
> book__title='not existing book')),
> ).select_related('empty_join')
> )
> }}}
> }}}
>
> This bug is typical since version 2.0 and exists until now.
New description:
When I try to join table with using `FilteredRelation` clause it failed if
the result of a joined table is null.
This error can be reproduce by adding the following test case to the
corresponding
[https://github.com/django/django/blob/2.0/tests/filtered_relation/tests.py#L9
test module]:
{{{#!div style="font-size: 80%"
tests.filtered_relation.tests.FilteredRelationTests:
{{{#!python
def test_select_related_empty_join(self):
self.assertFalse(
Author.objects.annotate(
empty_join=FilteredRelation('book', condition=Q(
book__title='not existing book')),
).select_related('empty_join')
)
}}}
}}}
{{{#!div style="font-size: 80%"
Error:
{{{
............E.s................
======================================================================
ERROR: test_select_related_empty_join
(filtered_relation.tests.FilteredRelationTests)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/usr/lib/python3.6/unittest/case.py", line 59, in testPartExecutor
yield
File "/usr/lib/python3.6/unittest/case.py", line 605, in run
testMethod()
File
"/home/adv/projects/github/django/tests/filtered_relation/tests.py", line
46, in test_select_related_empty_join
).select_related('empty_join')
File "/usr/lib/python3.6/unittest/case.py", line 674, in assertFalse
if expr:
File "/home/adv/projects/github/django/django/db/models/query.py", line
271, in __bool__
self._fetch_all()
File "/home/adv/projects/github/django/django/db/models/query.py", line
1232, in _fetch_all
self._result_cache = list(self._iterable_class(self))
File "/home/adv/projects/github/django/django/db/models/query.py", line
67, in __iter__
rel_populator.populate(row, obj)
File "/home/adv/projects/github/django/django/db/models/query.py", line
1876, in populate
self.local_setter(from_obj, obj)
File
"/home/adv/projects/github/django/django/db/models/sql/compiler.py", line
892, in local_setter
f.remote_field.set_cached_value(from_obj, obj)
File
"/home/adv/projects/github/django/django/db/models/fields/mixins.py", line
23, in set_cached_value
instance._state.fields_cache[self.get_cache_name()] = value
AttributeError: 'NoneType' object has no attribute '_state'
----------------------------------------------------------------------
}}}
}}}
This bug is typical since version 2.0 and exists until now.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/29810#comment:1>
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