#29897: Initial migration fails when referencing a custom user model from a
sequence of at least two concrete ancestor models
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
stevenganz |
Type: Bug | Status: new
Component: | Version: 2.1
Migrations |
Severity: Release | Keywords: "custom user model"
blocker | "abstract model" "foreign key"
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
The following model fails on initial migration.
{{{
from django.db import models
from django.contrib.auth.models import (AbstractBaseUser)
class A(models.Model):
createdByUser = models.ForeignKey('User', related_name='creations+',
verbose_name='creatorUser', blank=True, null=True, editable=False,
on_delete=models.PROTECT)
class B(A):
pass
class User(AbstractBaseUser, B):
email = models.EmailField('email address', max_length=256,
unique=True, db_index=True)
USERNAME_FIELD = 'email'
@property
def username(self):
return self.email
}}}
settings.py contains:
{{{
AUTH_USER_MODEL = 'core.User'
}}}
{{{
Applying core.0001_initial...Traceback (most recent call last):
File "./manage.py", line 13, in <module>
execute_from_command_line(sys.argv)
File ".../lib/python3.6/site-
packages/django/core/management/__init__.py", line 364, in
execute_from_command_line
utility.execute()
File ".../lib/python3.6/site-
packages/django/core/management/__init__.py", line 356, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File ".../lib/python3.6/site-packages/django/core/management/base.py",
line 283, in run_from_argv
self.execute(*args, **cmd_options)
File ".../lib/python3.6/site-packages/django/core/management/base.py",
line 330, in execute
output = self.handle(*args, **options)
File ".../lib/python3.6/site-
packages/django/core/management/commands/migrate.py", line 204, in handle
fake_initial=fake_initial,
File ".../lib/python3.6/site-packages/django/db/migrations/executor.py",
line 115, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake,
fake_initial=fake_initial)
File ".../lib/python3.6/site-packages/django/db/migrations/executor.py",
line 145, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake,
fake_initial=fake_initial)
File ".../lib/python3.6/site-packages/django/db/migrations/executor.py",
line 244, in apply_migration
state = migration.apply(state, schema_editor)
File ".../lib/python3.6/site-
packages/django/db/migrations/migration.py", line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File ".../lib/python3.6/site-
packages/django/db/migrations/operations/fields.py", line 88, in
database_forwards
field,
File ".../lib/python3.6/site-
packages/django/db/backends/base/schema.py", line 431, in add_field
definition, params = self.column_sql(model, field,
include_default=True)
File ".../lib/python3.6/site-
packages/django/db/backends/base/schema.py", line 160, in column_sql
db_params = field.db_parameters(connection=self.connection)
File ".../lib/python3.6/site-
packages/django/db/models/fields/related.py", line 994, in db_parameters
return {"type": self.db_type(connection), "check":
self.db_check(connection)}
File ".../lib/python3.6/site-
packages/django/db/models/fields/related.py", line 991, in db_type
return self.target_field.rel_db_type(connection=connection)
File ".../lib/python3.6/site-
packages/django/db/models/fields/related.py", line 909, in target_field
return self.foreign_related_fields[0]
File ".../lib/python3.6/site-
packages/django/db/models/fields/related.py", line 653, in
foreign_related_fields
return tuple(rhs_field for lhs_field, rhs_field in self.related_fields
if rhs_field)
File ".../lib/python3.6/site-
packages/django/db/models/fields/related.py", line 640, in related_fields
self._related_fields = self.resolve_related_fields()
File ".../lib/python3.6/site-
packages/django/db/models/fields/related.py", line 625, in
resolve_related_fields
raise ValueError('Related model %r cannot be resolved' %
self.remote_field.model)
ValueError: Related model 'core.User' cannot be resolved
}}}
Notably, this works fine with any of the following modifications:
- model B is removed, closing the chain
- createdByUser is moved to B or removed altogether
- either A or B is made abstract
- the referenced model is not the custom user model
This is not just a matter of preference for concrete classes, as only a
concrete class can be referenced through a foreign key.
--
Ticket URL: <https://code.djangoproject.com/ticket/29897>
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