Cannot run migrations that reference django.contrib.auth.models.User

[mario.pfeifer@…]

Hi,

To verify this bug I use a very simple model in which I reference to the User model:

from django.conf import settings
from django.db import models


class Article(models.Model):
    name = models.CharField('Name', max_length=255)
    author = models.ForeignKey(settings.AUTH_USER_MODEL)

After running ./manage.py makemigrations everything looks fine:

Do you want to enable migrations for app 'articles'? [y/N] y
Migrations for 'articles':
  0001_initial.py:
    - Create model Article

But running ./manage.py migrate runs into following error:

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/mario/django-trunk/django/core/management/__init__.py", line 397, in execute_from_command_line
    utility.execute()
  File "/home/mario/django-trunk/django/core/management/__init__.py", line 390, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/mario/django-trunk/django/core/management/base.py", line 242, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/mario/django-trunk/django/core/management/base.py", line 289, in execute
    output = self.handle(*args, **options)
  File "/home/mario/django-trunk/django/core/management/commands/migrate.py", line 88, in handle
    targets = executor.loader.graph.leaf_nodes()
  File "/home/mario/django-trunk/django/utils/functional.py", line 49, in __get__
    res = instance.__dict__[self.func.__name__] = self.func(instance)
  File "/home/mario/django-trunk/django/db/migrations/loader.py", line 169, in graph
    graph.add_dependency(key, parent)
  File "/home/mario/django-trunk/django/db/migrations/graph.py", line 40, in add_dependency
    raise KeyError("Dependency references nonexistent parent node %r" % (parent,))
KeyError: "Dependency references nonexistent parent node (u'auth', '0001_initial')"

The same happens when I directly reference to the User model:

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


class Article(models.Model):
    name = models.CharField('Name', max_length=255)
    author = models.ForeignKey(User)

[Baptiste Mispelon]

Hi,

I can reproduce the issue and from what I can tell, you're following the documentation (both for referencing the user model and for making/applying migrations) so this is most likely a bug.

Thanks for the detailed report.

[OBu]

I just ran into the same problem.
To add one more detail to the problem description:

0001_initial.py starts with
class Migration(migrations.Migration):

dependencies = [(u'auth', '0001_initial'), (u'my_app_name', 'first')]

[Tim Graham]

I've looked into adding migrations to contrib.auth, but ran into #21275. It's also unclear how migrations are supposed to work with "swappable" models like User. Obviously, we want to ignore it if a project uses a custom user.

[OBu]

...and to add to the list of problems: There is no migration __first__as well.
Removing the dependencies does not help since migrate is checking all foreign keys and it does not find information about foreign keys pointing to Users.

Since tried to add a --fake migration since in my current application I wanted to add just a boolean, but this still did not help since migrate traverses through all models fields.

To sum it up: No work arounds found, switching back to south :-(...

I don't have too much experience with django core development, but I would rate this bug a "release blocker"...

[Tim Graham]

Yes, migrations is still under active development. It was merged well before it was feature complete because reconciling changes on master with the external branch was a challenge. We will definitely review all migrations tickets before releasing 1.7.

[Tim Graham]

From Andrew on IRC: "My plan was that contrib apps would ship with migrations. Specifically, I'd like to ship auth with some straight in 1.7. Initial fake migrations will be handled by the new framework directly."

So this bug should be fixed in due time before the 1.7 release. Thanks for your patience.

[OBu]

Timo, thanks for keeping us updated! I'm really looking forward to the new migration system!

[Andrew Godwin]

Yes, sorry, you probably hit a part of the dependency resolution that was failing. It's supposed to depend on first, which if the application doesn't have migrations is ignored - I'll make sure it's doing that.

[Andrew Godwin <andrew@…>]

In 64887c644a8fe1004a15e27087d4e27c95c90fcd:

Fixed #21142: Dependency failures on unmigrated apps.

[anthony.arnold@…]

Was just Googling this error and discovered that it was pulled to master an hour and a half ago. Thanks, Internet.