Double proxy models break migrations
|Reported by:||Maik Hoepfel||Owned by:||Andrew Godwin|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
I'm working on adding Django 1.7 support to django-oscar. We have two layers of proxy models on top of a Benefit model. That is unorthodox and maybe not the best design decision, but worked in Django before 1.7. It breaks when trying to apply new-style migrations.
This happens both with the release candidate and a checkout from stable/1.7.x.
As a minimal test case, I created a new Django project and app, and have the following models:
from django.db import models class Benefit(models.Model): # not needed, just showing that the model isn't empty type = models.CharField("Type", max_length=128, blank=True) class ShippingBenefit(Benefit): class Meta: proxy = True class ShippingAbsoluteDiscountBenefit(ShippingBenefit): class Meta: proxy = True
I then run
rm -r testapp/migrations/ db.sqlite3 && ./manage.py makemigrations testapp && ./manage.py migrate to reproduce:
Migrations for 'testapp': 0001_initial.py: - Create model Benefit - Create proxy model ShippingAbsoluteDiscountBenefit - Create proxy model ShippingBenefit Operations to perform: Apply all migrations: admin, contenttypes, testapp, auth, sessions Running migrations: Applying contenttypes.0001_initial... OK Applying auth.0001_initial... OK Applying admin.0001_initial... OK Applying sessions.0001_initial... OK Applying testapp.0001_initial...Traceback (most recent call last): File "./manage.py", line 10, in <module> execute_from_command_line(sys.argv) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line utility.execute() File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv self.execute(*args, **options.__dict__) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/core/management/base.py", line 337, in execute output = self.handle(*args, **options) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 160, in handle executor.migrate(targets, plan, fake=options.get("fake", False)) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 62, in migrate self.apply_migration(migration, fake=fake) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 96, in apply_migration migration.apply(project_state, schema_editor) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/db/migrations/migration.py", line 107, in apply operation.database_forwards(self.app_label, schema_editor, project_state, new_state) File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/db/migrations/operations/models.py", line 33, in database_forwards apps = to_state.render() File "/home/m/.virtualenvs/proxyfun/local/lib/python2.7/site-packages/django/db/migrations/state.py", line 71, in render raise InvalidBasesError("Cannot resolve bases for %r\nThis can happen if you are inheriting models from an app with migrations (e.g. contrib.auth)\n in an app with no migrations; see https://docs.djangoproject.com/en/1.7/topics/migrations/#dependencies for more" % new_unrendered_models) django.db.migrations.state.InvalidBasesError: Cannot resolve bases for [<ModelState: 'testapp.ShippingAbsoluteDiscountBenefit'>] This can happen if you are inheriting models from an app with migrations (e.g. contrib.auth) in an app with no migrations; see https://docs.djangoproject.com/en/1.7/topics/migrations/#dependencies for more