#22931: Migrations cannot rename intermediate models
-------------------------------------+-------------------------------------
Reporter: JockeTF | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.7-rc-1
(models, ORM) | Keywords: migrations migrate
Severity: Normal | makemigrations rename intermediate
Triage Stage: Unreviewed | model
Easy pickings: 0 | Has patch: 0
| UI/UX: 0
-------------------------------------+-------------------------------------
Due to a change in naming conventions I needed to rename an intermediate
model. I renamed a model from Subscriber to Subscribe.
{{{#!python
from django.db import models
from django.conf import settings
class Channel(models.Model):
name = models.CharField(max_length=128)
subscribers = models.ManyToManyField(settings.AUTH_USER_MODEL,
through='Subscribe', related_name='subscriptions')
date_created = models.DateTimeField(auto_now_add=True)
class Subscribe(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL)
channel = models.ForeignKey(Channel)
date_subscribed = models.DateTimeField(auto_now_add=True)
class Meta():
unique_together = ('user', 'channel')
}}}
Running makemigrations in Django 1.7c1 results in an exception.
{{{#!python
0002_auto_20140701_0817.py:
- Create model Subscribe
- Alter unique_together for subscribe (1 constraints)
Traceback (most recent call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/__init__.py", line 385, in
execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/__init__.py", line 377, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/base.py", line 288, in run_from_argv
self.execute(*args, **options.__dict__)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/base.py", line 337, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/commands/makemigrations.py", line 115, in
handle
self.write_migration_files(changes)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/commands/makemigrations.py", line 131, in
write_migration_files
self.stdout.write(" - %s\n" % operation.describe())
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/operations/models.py", line 251, in describe
return "Alter %s for %s (%s constraints)" % (self.option_name,
self.name, len(self.unique_together))
TypeError: object of type 'NoneType' has no len()
}}}
In Django 1.7b3 makemigrations actually worked.
{{{#!python
from django.db import models, migrations
from django.conf import settings
class Migration(migrations.Migration):
dependencies = [
('api', '0002_auto_20140630_1443'),
]
operations = [
migrations.RenameModel(
old_name='Subscriber',
new_name='Subscribe',
),
migrations.AlterField(
model_name='channel',
name='subscribers',
field=models.ManyToManyField(through='api.Subscribe',
to=settings.AUTH_USER_MODEL),
),
]
}}}
However, running migrate in Django 1.7b3 results in another exception.
{{{#!python
Running migrations:
Applying api.0013_subscriber_renamed...Traceback (most recent call
last):
File "/usr/local/lib/python3.4/dist-packages/django/apps/config.py",
line 152, in get_model
return self.models[model_name.lower()]
KeyError: 'subscriber'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/state.py", line 78, in render
model = self.apps.get_model(lookup_model[0], lookup_model[1])
File "/usr/local/lib/python3.4/dist-packages/django/apps/registry.py",
line 190, in get_model
return self.get_app_config(app_label).get_model(model_name.lower())
File "/usr/local/lib/python3.4/dist-packages/django/apps/config.py",
line 155, in get_model
"App '%s' doesn't have a '%s' model." % (self.label, model_name))
LookupError: App 'api' doesn't have a 'subscriber' model.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/__init__.py", line 385, in
execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/__init__.py", line 377, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/base.py", line 288, in run_from_argv
self.execute(*args, **options.__dict__)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/base.py", line 337, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python3.4/dist-
packages/django/core/management/commands/migrate.py", line 146, in handle
executor.migrate(targets, plan, fake=options.get("fake", False))
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/executor.py", line 62, in migrate
self.apply_migration(migration, fake=fake)
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/executor.py", line 96, in apply_migration
migration.apply(project_state, schema_editor)
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/migration.py", line 107, in apply
operation.database_forwards(self.app_label, schema_editor,
project_state, new_state)
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/operations/models.py", line 141, in
database_forwards
new_apps = to_state.render()
File "/usr/local/lib/python3.4/dist-
packages/django/db/migrations/state.py", line 88, in render
model=lookup_model,
ValueError: Lookup failed for model referenced by field
api.Channel.subscribers: api.Subscriber
}}}
The same exception is thrown if I move the migration generated in Django
1.7b3 to Django 1.7c1.
--
Ticket URL: <https://code.djangoproject.com/ticket/22931>
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