ValueError during migrations.RunPython to create OneToOne records in new model

[Gergely Polonkai]

Hello,

I have created a new model called Settings, which has a OneToOneField(User, primary_key=True) field. After the automatically created migrations.CreateModel() invocation I added a RunPython line that runs this function:

def create_user_settings(apps, schema_editor):

    User = get_user_model()

    Settings = apps.get_model('accounts', 'Settings')

    for user in User.objects.all():

        Settings.objects.get_or_create(user=user) # This is line 13

When running this migration, I get the following error:

Traceback (most recent call last):

  File "manage.py", line 10, in <module>

    execute_from_command_line(sys.argv)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line

    utility.execute()

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/core/management/__init__.py", line 330, in execute

    self.fetch_command(subcommand).run_from_argv(self.argv)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/core/management/base.py", line 390, in run_from_argv

    self.execute(*args, **cmd_options)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/core/management/base.py", line 441, in execute

    output = self.handle(*args, **options)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 221, in handle

    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/migrations/executor.py", line 110, in migrate

    self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/migrations/executor.py", line 147, in apply_migration

    state = migration.apply(state, schema_editor)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/migrations/migration.py", line 115, in apply

    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/migrations/operations/special.py", line 183, in database_forwards

    self.code(from_state.apps, schema_editor)

  File "/home/polesz/Projects/dem/accounts/migrations/0003_settings.py", line 13, in create_user_settings

    Settings.objects.get_or_create(user=user)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/manager.py", line 127, in manager_method

    return getattr(self.get_queryset(), name)(*args, **kwargs)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/query.py", line 405, in get_or_create

    return self.get(**lookup), False

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/query.py", line 325, in get

    clone = self.filter(*args, **kwargs)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/query.py", line 679, in filter

    return self._filter_or_exclude(False, *args, **kwargs)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/query.py", line 697, in _filter_or_exclude

    clone.query.add_q(Q(*args, **kwargs))

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1306, in add_q

    clause, require_inner = self._add_q(where_part, self.used_aliases)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1333, in _add_q

    current_negated=current_negated, connector=connector, allow_joins=allow_joins)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1175, in build_filter

    self.check_related_objects(field, value, opts)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1070, in check_related_objects

    self.check_query_object_type(value, opts)

  File "/home/polesz/Projects/dem/venv/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1054, in check_query_object_type

    (value, opts.object_name))

ValueError: Cannot query "polesz": Must be "User" instance.

While debugging, it turns out that the value of the user variable is indeed a User instance. Do I miss some key information here? Maybe apps are not fully initialized when I run migrations?

Best,

Gergely

[Markus Holtermann]

Hi Gergely,

You need to use apps.get_model() instead of get_user_model(). See https://docs.djangoproject.com/en/1.8/topics/migrations/#data-migrations

/Markus

[Gergely Polonkai]

Hello Markus,

thanks for the pointer. Just for the record, if you want to use it in a reusable app, you should do this:

User = apps.get_model(django.conf.settings.AUTH_USER_MODEL)

Best,

Gergely

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