Error during application of M2M migrations #56

raphaelm · 2015-02-11T20:39:55Z

During running an auto-generated migration, I run into

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/core/management/commands/sqlmigrate.py", line 30, in execute
    return super(Command, self).execute(*args, **options)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/core/management/commands/sqlmigrate.py", line 61, in handle
    sql_statements = executor.collect_sql(plan)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/db/migrations/executor.py", line 82, in collect_sql
    migration.apply(project_state, schema_editor, collect_sql=True)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/db/migrations/migration.py", line 108, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/db/migrations/operations/fields.py", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/db/backends/schema.py", line 445, in alter_field
    return self._alter_many_to_many(model, old_field, new_field, strict)
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/db/backends/sqlite3/schema.py", line 229, in _alter_many_to_many
    old_field.rel.through._meta.get_field_by_name(old_field.m2m_reverse_field_name())[0],
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/utils/functional.py", line 17, in _curried
    return _curried_func(*(args + moreargs), **dict(kwargs, **morekwargs))
  File "/daten/proj/pretix/env/lib/python3.4/site-packages/django/db/models/fields/related.py", line 2221, in _get_m2m_reverse_attr
    return getattr(self, cache_attr)
AttributeError: 'VersionedManyToManyField' object has no attribute '_m2m_reverse_name_cache'

The migration looks like

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models, migrations
import versions.models
import pretixbase.models


class Migration(migrations.Migration):

    dependencies = [
        ('pretixbase', '0002_auto_20150211_2031'),
    ]

    operations = [
        migrations.AlterField(
            model_name='quota',
            name='items',
            field=versions.models.VersionedManyToManyField(verbose_name='Item', to='pretixbase.Item', blank=True, related_name='quotas'),
            preserve_default=True,
        ),
    ]

I'm not 100% sure but I'm fairly certain that the migration was created because I explicitely set the related_name attribute, while it was auto-generated before. Do you think there is an easy way to solve this?

The text was updated successfully, but these errors were encountered:

swisscom/cleanerversion#56

brandonmoser · 2015-07-21T15:29:55Z

I'm receiving the same error while trying to run a migration with an VM2M field, but was unable to get the above workaround to fix the error. Here is the snippet of the migration that references a VersionedManyToManyField.

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models, migrations
import datetime
from django.utils.timezone import utc
import versions.models
import model_utils.fields
import shared.utils
import django_hstore.fields
import django_hstore.virtual
import ckeditor.fields
import django.utils.timezone


class Migration(migrations.Migration):

    dependencies = [
        ('django_hstore', '__first__'),
        ('webassess', '0002_remove_assessmentquestions'),
    ]

    operations = [
        ...
        migrations.AlterField(
            model_name='assessmentbattery',
            name='assessments',
            field=versions.models.VersionedManyToManyField(to='webassess.Assessment'),
            preserve_default=True,
        ),
        ...
    ]

If I add a related_name= attribute, as suggested above, it still fails with the same error,
_AttributeError: 'VersionedManyToManyField' object has no attribute 'm2m_reverse_name_cache'

Here is my traceback for reference (similar to above TB, except Python2.7):

Traceback (most recent call last):
  File "manage.py", line 11, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/sqlmigrate.py", line 30, in execute
    return super(Command, self).execute(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/sqlmigrate.py", line 61, in handle
    sql_statements = executor.collect_sql(plan)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 82, in collect_sql
    migration.apply(project_state, schema_editor, collect_sql=True)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/migration.py", line 108, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/operations/fields.py", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "/usr/local/lib/python2.7/dist-packages/django/db/backends/schema.py", line 460, in alter_field
    return self._alter_many_to_many(model, old_field, new_field, strict)
  File "/usr/local/lib/python2.7/dist-packages/django/db/backends/schema.py", line 764, in _alter_many_to_many
    new_field.rel.through._meta.get_field_by_name(new_field.m2m_reverse_field_name())[0],
  File "/usr/local/lib/python2.7/dist-packages/django/utils/functional.py", line 17, in _curried
    return _curried_func(*(args + moreargs), **dict(kwargs, **morekwargs))
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 2224, in _get_m2m_reverse_attr
    return getattr(self, cache_attr)
AttributeError: 'VersionedManyToManyField' object has no attribute '_m2m_reverse_name_cache'

maennel · 2015-10-18T00:05:16Z

So, I've managed to write a test case that reproduces this issue reliably (see branch bugfix/reproduce_failing_vm2m_migration and the commit above). Unfortunately, I'll have to postpone the follow-up to some other day...

maennel · 2015-10-19T13:57:22Z

So far, I've managed to work around the first error that is described above. However, there's more! ;)
It seems that in general, Django migrations don't get along very well with M2M-intermediary models that are Versionable at the same time (so, basically any VersionedManyToManyField being defined).
Finally I got to the following error:

Error
Traceback (most recent call last):
  File "/vagrant/migrations_tests/tests/test_migrations.py", line 55, in test_migration
    self.assertRaises(AttributeError, self.run_migration)
  File "/usr/lib/python2.7/unittest/case.py", line 475, in assertRaises
    callableObj(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/django_migration_testcase/django_migrations.py", line 39, in run_migration
    verbosity=0, no_initial_data=True)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 115, in call_command
    return klass.execute(*args, **defaults)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/migrate.py", line 161, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 68, in migrate
    self.apply_migration(migration, fake=fake)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 102, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/migration.py", line 108, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/operations/fields.py", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "/usr/local/lib/python2.7/dist-packages/django/db/backends/schema.py", line 460, in alter_field
    return self._alter_many_to_many(model, old_field, new_field, strict)
  File "/usr/local/lib/python2.7/dist-packages/django/db/backends/sqlite3/schema.py", line 234, in _alter_many_to_many
    override_uniques=(new_field.m2m_field_name(), new_field.m2m_reverse_field_name()),
  File "/usr/local/lib/python2.7/dist-packages/django/db/backends/sqlite3/schema.py", line 135, in _remake_table
    temp_model = type(model._meta.object_name, model.__bases__, body)
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 229, in __new__
    'base class %r' % (field.name, name, base.__name__)
FieldError: Local field 'id' in class 'mymigratingmodelb_a_models' clashes with field of similar name from base class 'Versionable'

It's raised because during a migration, new intermediary classes are created, and, since deepcopied from an already existing intermediary class, are conflicting when their parent class' (Versionable) properties are being set up (id, identity, version_from, etc.).
I've committed my stuff to the following branch: https://github.com/swisscom/cleanerversion/tree/bugfix/fix_failing_vm2m_migration
I'm doing tests on Django 1.7.10

maennel · 2016-01-05T13:41:39Z

I've been pointed to Django's ticket #25154 which was obviously opened by @brandonmoser. Thanks for that, I think the way it's going will be helpful.
Also, there's a patch suggested by @MarkusH which can be found here which could help for further debugging.

raphaelm added a commit to pretix/pretix that referenced this issue Feb 12, 2015

Workaround a migration hiccup caused by

98db147

swisscom/cleanerversion#56

maennel added a commit that referenced this issue Oct 17, 2015

Added a reproducing case for the VM2M migration issue described in #56

b9b6038

maennel mentioned this issue Dec 28, 2016

Django19 compatibility #127

Closed

maennel changed the title ~~Error during migrations~~ Error during application of M2M migrations Jan 30, 2017

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Error during application of M2M migrations #56

Error during application of M2M migrations #56

raphaelm commented Feb 11, 2015

brandonmoser commented Jul 21, 2015

maennel commented Oct 18, 2015

maennel commented Oct 19, 2015

maennel commented Jan 5, 2016

Error during application of M2M migrations #56

Error during application of M2M migrations #56

Comments

raphaelm commented Feb 11, 2015

brandonmoser commented Jul 21, 2015

maennel commented Oct 18, 2015

maennel commented Oct 19, 2015

maennel commented Jan 5, 2016