#30381: django/contrib/auth/migrations/0011_update_proxy_permissions.py can
cause a
unique constraint violation
----------------------------------------+------------------------
Reporter: Jon Dufresne | Owner: nobody
Type: Bug | Status: new
Component: contrib.auth | Version: 2.2
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
----------------------------------------+------------------------
Use an existing database that was migrated using Django 2.1. This must
contain auth permissions for proxy models. Per Django 2.1,
`Permission.content_type` points to the concrete model's content type, not
the proxy's.
Once this database exists, steps to reproduce:
1. Run a subset of migrations that includes the proxy model's app but does
not include `0011_update_proxy_permissions`.
2. This triggers the auth `create_permissions()` post migrate handler.
3. `create_permissions()` generates new permissions for the proxy models
that point to the proxy content type. The old ones that point to the
concrete model still exist.
4. Now run all migrations.
5. `auth.0011_update_proxy_permissions` runs and tries to update the pre-
existing proxy models. But as the auth permissions were already created
during the previous migration run, this crashes with a unique constraint
violation.
Traceback (PostgreSQL backend):
{{{
Traceback (most recent call last):
...
File ".../venv/lib64/python3.7/site-
packages/django/core/management/commands/migrate.py", line 234, in handle
fake_initial=fake_initial,
File ".../venv/lib64/python3.7/site-
packages/django/db/migrations/executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake,
fake_initial=fake_initial)
File ".../venv/lib64/python3.7/site-
packages/django/db/migrations/executor.py", line 147, in
_migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake,
fake_initial=fake_initial)
File ".../venv/lib64/python3.7/site-
packages/django/db/migrations/executor.py", line 245, in apply_migration
state = migration.apply(state, schema_editor)
File ".../venv/lib64/python3.7/site-
packages/django/db/migrations/migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File ".../venv/lib64/python3.7/site-
packages/django/db/migrations/operations/special.py", line 190, in
database_forwards
self.code(from_state.apps, schema_editor)
File ".../venv/lib64/python3.7/site-
packages/django/contrib/auth/migrations/0011_update_proxy_permissions.py",
line 30, in update_proxy_model_permissions
).update(content_type=new_content_type)
File ".../venv/lib64/python3.7/site-packages/django/db/models/query.py",
line 741, in update
rows = query.get_compiler(self.db).execute_sql(CURSOR)
File ".../venv/lib64/python3.7/site-
packages/django/db/models/sql/compiler.py", line 1426, in execute_sql
cursor = super().execute_sql(result_type)
File ".../venv/lib64/python3.7/site-
packages/django/db/models/sql/compiler.py", line 1097, in execute_sql
cursor.execute(sql, params)
File ".../venv/lib64/python3.7/site-
packages/django/db/backends/utils.py", line 99, in execute
return super().execute(sql, params)
File ".../venv/lib64/python3.7/site-
packages/django/db/backends/utils.py", line 67, in execute
return self._execute_with_wrappers(sql, params, many=False,
executor=self._execute)
File ".../venv/lib64/python3.7/site-
packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
return executor(sql, params, many, context)
File ".../venv/lib64/python3.7/site-
packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File ".../venv/lib64/python3.7/site-packages/django/db/utils.py", line
89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File ".../venv/lib64/python3.7/site-
packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: duplicate key value violates unique
constraint "auth_permission_content_type_id_01ab375a_uniq"
DETAIL: Key (content_type_id, codename)=(168, add_myproxymodel) already
exists.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/30381>
Django <https://code.djangoproject.com/>
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