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

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

On June 17, 2015 12:48:48 PM GMT+02:00, Gergely Polonkai <gergely@polonkai.eu> wrote:
>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

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