[Django] #26105: create_permissions uses ContentType cache which contains non-existing pks
Django
----------------------------------------------+--------------------
Reporter: srkunze | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: 1.8
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
----------------------------------------------+--------------------
While migrating a larger project, we found the traceback attached.
We found that create_permissions from
{{{django/contrib/auth/management/__init__.py}}} uses the {{{
ContentType.objects._cache }}} instead of querying the database for the
real pk of the contenttype.
Real pks from database:
{{{
id | app_label | model
-----+-----------------------+--------------------------------------------
1 | auth | permission
2 | auth | group
3 | auth | user
}}}
Pks generated by django (execution at breakpoint at line 103):
{{{
>>> [(id, ct) for id, ct in ContentType.objects._cache['default'].items()
if ct.app_label == 'auth']
[
(2, <ContentType: group>),
(3, <ContentType: permission>),
(4, <ContentType: user>),
]
}}}
It seems Django confused real pks with imaginary pks. We created a
placeholder contenttype with pk=4 before rerunning the migrations, which
fixed the exception but created a new permission linked to this "false"
contenttype.
If the contenttype with pk=4 were a real one (i.e. an existing model
etc.), a wrong permission would have been created then.
{{{
=> select * from django_content_type where id=4;
id | app_label | model
----+-----------+---------------
4 | auth | XXXXXXXXXXXXX
=> select * from auth_permission where content_type_id=4;
id | name | content_type_id | codename
-----+-----------------+-----------------+-------------
598 | Can delete user | 4 | delete_user
597 | Can change user | 4 | change_user
596 | Can add user | 4 | add_user
}}}
The migration traceback:
{{{
Traceback (most recent call last):
File "lib/python2.7/site-packages/django/core/management/__init__.py",
line 354, in execute_from_command_line
utility.execute()
File "lib/python2.7/site-packages/django/core/management/__init__.py",
line 346, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "lib/python2.7/site-packages/django/core/management/base.py", line
394, in run_from_argv
self.execute(*args, **cmd_options)
File "lib/python2.7/site-packages/django/core/management/base.py", line
445, in execute
output = self.handle(*args, **options)
File "lib/python2.7/site-
packages/django/core/management/commands/migrate.py", line 226, in handle
emit_post_migrate_signal(created_models, self.verbosity,
self.interactive, connection.alias)
File "lib/python2.7/site-packages/django/core/management/sql.py", line
280, in emit_post_migrate_signal
using=db)
File "lib/python2.7/site-packages/django/dispatch/dispatcher.py", line
189, in send
response = receiver(signal=self, sender=sender, **named)
File "lib/python2.7/site-
packages/django/contrib/auth/management/__init__.py", line 114, in
create_permissions
Permission.objects.using(using).bulk_create(perms)
File "lib/python2.7/site-packages/django/db/models/query.py", line 392,
in bulk_create
self._batched_insert(objs_without_pk, fields, batch_size)
File "lib/python2.7/site-packages/django/db/transaction.py", line 225,
in __exit__
connection.commit()
File "lib/python2.7/site-packages/django/db/backends/base/base.py", line
173, in commit
self._commit()
File "lib/python2.7/site-packages/django/db/backends/base/base.py", line
142, in _commit
return self.connection.commit()
File "lib/python2.7/site-packages/django/db/utils.py", line 98, in
__exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "lib/python2.7/site-packages/django/db/backends/base/base.py", line
142, in _commit
return self.connection.commit()
django.db.utils.IntegrityError: insert or update on table
"auth_permission" violates foreign key constraint
"auth_content_type_id_508cf46651277a81_fk_django_content_type_id"
DETAIL: Key (content_type_id)=(4) is not present in table
"django_content_type".
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/26105>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
Reporter: srkunze | Owner: nobody
Type: Bug | Status: new
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Changes (by srkunze):
* needs_better_patch: => 0
* needs_tests: => 0
* needs_docs: => 0
Comment:
A quick fix we found could be (line 90 to line 100):
{{{
all_perms=set(Permission.objects.using(using).filter(
content_type__in=ctypes,
).values_list(
"content_type__app_label", "content_type__model", "codename"
))
perms = [
Permission(codename=codename, name=name, content_type=ct)
for ct, (codename, name) in searched_perms
if (ct.app_label, ct.model, codename) not in all_perms
]
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/26105#comment:1>
Django
Reporter: srkunze | Owner: nobody
Type: Bug | Status: new
(models, ORM) |
Severity: Normal | Resolution:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by timgraham):
Might be a duplicate of #10827. Could you test the fix proposed on that
ticket? We're still waiting for a test for that patch if you're able to
provide one.
--
Ticket URL: <https://code.djangoproject.com/ticket/26105#comment:2>
Django
Reporter: srkunze | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 1.8
(models, ORM) |
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by srkunze):
* status: new => closed
* resolution: => duplicate
Comment:
It seems it is.
--
Ticket URL: <https://code.djangoproject.com/ticket/26105#comment:3>
Django
Reporter: srkunze | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 1.8
(models, ORM) |
Severity: Normal | Resolution: duplicate
| Unreviewed
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by TZanke):
* cc: tzanke@… (added)
--
Ticket URL: <https://code.djangoproject.com/ticket/26105#comment:4>