#21203 closed Bug (fixed)
Potential data corruption issue with Oracle and Mysql due to SQLCompiler.resolve_columns row, fields misalignment when using defer and select_related
Reported by: | Michael Manfre | Owned by: | nobody |
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Component: | Database layer (models, ORM) | Version: | 1.5 |
Severity: | Release blocker | Keywords: | |
Cc: | Anssi Kääriäinen | Triage Stage: | Ready for checkin |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
SQLCompiler.resolve_columns fields, values are misaligned with defer and select_related. Same data corruption issue as reported/fixed by issue #21126.
Given:
class Parent(models.Model): parentid = models.AutoField(primary_key=True) parent_bool = models.BooleanField(default=True) created = models.DateTimeField(auto_now=True) class Child(models.Model): childid = models.AutoField(primary_key=True) parent = models.ForeignKey(Parent)
The following query
p = Parent.objects.create(parent_bool=True) c = Child.objects.create(parent=p) qs = Child.objects.all().select_related('parent').defer('parent__parent_bool')
will result in this field misalignment
field=<django.db.models.fields.AutoField: childid> value=1 field=<django.db.models.fields.related.ForeignKey: parent> value=1 field=<django.db.models.fields.AutoField: parentid> value=1 field=<django.db.models.fields.BooleanField: parent_bool> value=datetime.datetime(2013, 9, 30, 19, 59, 41, 490000, tzinfo=<UTC>) field=<django.db.models.fields.DateTimeField: created> value=None
parent_bool should have been removed from fields, but it was not because results_iter doesn't properly compare the only_load fields to the correct db_table1.
1 https://github.com/django/django/blob/master/django/db/models/sql/compiler.py#L716
Change History (5)
comment:1 by , 11 years ago
comment:2 by , 11 years ago
Triage Stage: | Unreviewed → Accepted |
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comment:3 by , 11 years ago
Triage Stage: | Accepted → Ready for checkin |
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The pull request fixes the simple example I included above and the issue as experienced in my full project.
Here's a pull request for the backpatch to 1.5.x :)
https://github.com/django/django/pull/1701
(ignore previous edit, venv was corrupted and including an unpatched django from a different venv)
comment:4 by , 11 years ago
Resolution: | → fixed |
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Status: | new → closed |
Pull request https://github.com/django/django/pull/1698 should solve this ticket.
The basic problem was that the only_load dictionary wasn't used correctly.
Unfortunately the only_load dictionary also contains wrong data in some complex situations, but that is not this ticket's problem. I will create another ticket for that issue.