auth.0001_initial migration fails when there is a custom user model

[Vidir Valberg Gudmundsson]

Models

from django.db import models
from django.contrib.auth.models import AbstractUser


class Profile(AbstractUser):
    title = models.CharField(max_length=255)

Migration

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models, migrations
import django.core.validators
import django.utils.timezone


class Migration(migrations.Migration):

    dependencies = [
        ('auth', '__first__'),
    ]

    operations = [
        migrations.CreateModel(
            name='Profile',
            fields=[
                ('id', models.AutoField(serialize=False, verbose_name='ID', auto_created=True, primary_key=True)),
                ('password', models.CharField(max_length=128, verbose_name='password')),
                ('last_login', models.DateTimeField(default=django.utils.timezone.now, verbose_name='last login')),
                ('is_superuser', models.BooleanField(default=False, help_text='Designates that this user has all permissions without explicitly assigning them.', verbose_name='superuser status')),
                ('username', models.CharField(help_text='Required. 30 characters or fewer. Letters, digits and @/./+/-/_ only.', max_length=30, unique=True, validators=[django.core.validators.RegexValidator('^[\\w.@+-]+$', 'Enter a valid username.', 'invalid')], verbose_name='username')),
                ('first_name', models.CharField(max_length=30, blank=True, verbose_name='first name')),
                ('last_name', models.CharField(max_length=30, blank=True, verbose_name='last name')),
                ('email', models.EmailField(max_length=75, blank=True, verbose_name='email address')),
                ('is_staff', models.BooleanField(default=False, help_text='Designates whether the user can log into this admin site.', verbose_name='staff status')),
                ('is_active', models.BooleanField(default=True, help_text='Designates whether this user should be treated as active. Unselect this instead of deleting accounts.', verbose_name='active')),
                ('date_joined', models.DateTimeField(default=django.utils.timezone.now, verbose_name='date joined')),
                ('title', models.CharField(max_length=255)),
                ('groups', models.ManyToManyField(blank=True, to='auth.Group', verbose_name='groups')),
                ('user_permissions', models.ManyToManyField(blank=True, to='auth.Permission', verbose_name='user permissions')),
            ],
            options={
                'abstract': False,
                'verbose_name_plural': 'users',
                'verbose_name': 'user',
            },
            bases=(models.Model,),
        ),
    ]

Error

$ ./manage.py migrate
Operations to perform:
  Synchronize unmigrated apps: (none)
  Apply all migrations: testapp, sessions, contenttypes, auth, admin
Synchronizing apps without migrations:
  Creating tables...
  Installing custom SQL...
  Installing indexes...
Running migrations:
  Applying auth.0001_initial...Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/valberg/Code/forks/django/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/Users/valberg/Code/forks/django/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/valberg/Code/forks/django/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/valberg/Code/forks/django/django/core/management/base.py", line 337, in execute
    output = self.handle(*args, **options)
  File "/Users/valberg/Code/forks/django/django/core/management/commands/migrate.py", line 146, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/Users/valberg/Code/forks/django/django/db/migrations/executor.py", line 62, in migrate
    self.apply_migration(migration, fake=fake)
  File "/Users/valberg/Code/forks/django/django/db/migrations/executor.py", line 96, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/Users/valberg/Code/forks/django/django/db/migrations/migration.py", line 107, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/Users/valberg/Code/forks/django/django/db/migrations/operations/models.py", line 36, in database_forwards
    schema_editor.create_model(model)
  File "/Users/valberg/Code/forks/django/django/db/backends/schema.py", line 282, in create_model
    if field.rel.through._meta.auto_created:
AttributeError: 'NoneType' object has no attribute '_meta'

Occurrences

This happens at 57a770b8e586399926311d86639c6789a1563253 in stable/1.7.x and 61d7ae31cf286277ddefaf8006597be40388d2ee in master.

[Tim Graham]

One solution is to specify your own MIGRATION_MODULES for auth, e.g. {'auth': 'testapp.migrations'} (since you don't want the table for auth.models.User anyway). I wonder if we should ship that migration (without the user model) with Django. Then we might be able to use it automatically if AUTH_USER_MODEL is in use.

Actually, should the fact the the model has been swapped out cause it to be ignored?

I think we can consolidate #22854 ("Having custom user model creates migrations in django.contrib.auth") with this ticket as well.

[Andrew Godwin]

The problem is that we can't just ignore the model when it's swapped out, as you can swap it back in _at any time_ and Django is supposed to work.

We have three options here:

• Just don't apply any operations on swapped models, like if they were denied routing or were managed=False. If you unswap them, you have to manually undo and reapply the auth migrations.
• Change it so that M2Ms are fully populated on swapped-out models and make the tables anyway so you can swap them back in at any time (but this clutters up the database with needless migrations)
• Make people do this custom migration modules thing.

My opinion is that we should ignore operations on swapped models (the first one), and make it very, very clear that you should not change AUTH_USER_MODEL after starting the project without expecting some serious pain or manual kerfuffling with migrate --fake. Thoughts?

[Vidir Valberg Gudmundsson]

Of the three options I'm also leaning towards the third one, mainly because doing this custom migration thing is confusing, and having a cluttered database is no fun!

But what about the option of having a migration that will be used if and only if AUTH_USER_MODEL != 'auth.User'? This should of course be generalized so it is doable with everything swappable.

[anonymous]

If you want to lock AUTH_USER_MODEL and not change it in future, Whats the idea of migration then? Does not make sense to me do it halfway like this.

[Andrew Godwin]

I mean, we already have the case where you can't really change AUTH_USER_MODEL midway, as any FKs that have already been created point to the old one. We're just restating the current state of things (and probably putting a much more obvious callout in the docs).

I'll go implement the first idea now.

Anonymous: The idea of migrations is to allow you to evolve the project as it changes. Changing AUTH_USER_MODEL essentially rewrites a whole load of foreign keys to point to a different table with different data that probably isn't even there; changing mid-project already means managing the move of data from auth.User to the new table. The option is there so you can start with your own user model and still use Django's admin and other tools.

[Andrew Godwin <andrew@…>]

In 8d2ac948a9583220d2324cf908bff3cc1d0beb2b:

Fixed #22853: Swapped models are now ignored for migration operations.

[Andrew Godwin <andrew@…>]

In f355d253f81c78b595e25e84309b648c24208d73:

[1.7.x] Fixed #22853: Swapped models are now ignored for migration operations.