#29897: Initial migration fails when referencing a custom user model from a
sequence of at least two concrete ancestor models
-------------------------------------+-------------------------------------
Reporter: stevenganz | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 2.1
Severity: Normal | Resolution:
Keywords: "custom user model" | Triage Stage: Accepted
"abstract model" "foreign key" |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Old description:
> 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.
New description:
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'
}}}
Output of running the migrations:
{{{
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.
--
Comment (by stevenganz):
I accidentally reset your changes to several fields -- please check that
I've restored them appropriately.
This was for an initial migration. Like you, I reproduced it on 1.11 &
2.1.
Your first work-around didn't work for me (perhaps because my actual
models are much more complex), but the second (temporarily updating the
custom user model) does. Thanks, and let me know if you need any more
information.
--
Ticket URL: <https://code.djangoproject.com/ticket/29897#comment:3>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
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