Opened 6 years ago

Last modified 6 years ago

#29810 closed Bug

Left outer join using FilteredRelation failed on empty result — at Version 1

Reported by: Dmitrii Azarenko Owned by: nobody
Component: Database layer (models, ORM) Version: dev
Severity: Normal Keywords: ORM FilteredRelation
Cc: Can Sarıgöl Triage Stage: Accepted
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description (last modified by Dmitrii Azarenko)

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 ​test module:

tests.filtered_relation.tests.FilteredRelationTests: 

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')
    )

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.

Change History (1)

comment:1 by Dmitrii Azarenko, 6 years ago

Description: modified (diff)
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