#29149: django-admin migrate fails on 2.0 when a project contains squashed
migrations from an earlier version
--------------------------------------+------------------------
Reporter: dcollinsn | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 2.0
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
--------------------------------------+------------------------
Hello,
Upgrading a project from 1.X to 2.0. One of my apps contains the following
migrations:
{{{
dcollins@digitalis:~/judgeappstest$ ls exams/migrations/ | grep -v .pyc
0001_squashed_0002_auto_20170519_2125.py
0002_examname.py
0003_exam_editors.py
0004_exam_question_log.py
0005_exam_admin.py
0006_examquestion_topics.py
0007_examtoquestion_option_order.py
0008_exam_for_other_user.py
0009_printed_exams.py
0010_exam_cooldown.py
0011_exam_accepts_suggestions.py
0012_exam_translations.py
0013_examtype_sortkey.py
0014_create_for_others_gk.py
0015_translated_question_reviewed.py
0016_translate_cards.py
0017_card_empty_oracle.py
}}}
The first such migration was squashed multiple times (0001 through 000X
were squashed, and then that migration was squashed into what we have
now). Samples from that migration file:
{{{
class Migration(migrations.Migration):
replaces = [(b'exams', '0001_squashed_0002_auto_20170518_1851'),
(b'exams', '0002_auto_20170519_2125')]
}}}
{{{
migrations.CreateModel(
name='ExamQuestion',
fields=[
('id', models.AutoField(verbose_name='ID',
serialize=False, auto_created=True, primary_key=True)),
('author', models.ForeignKey(on_delete=models.CASCADE,
to=settings.AUTH_USER_MODEL)),
],
),
}}}
After upgrading to Python 3.6/Django 2.0, when attempting to run
`migrate`, I get the following errors:
{{{
root@ubuntu-xenial:/dcif# python3 manage.py migrate gatekeeper
System check identified some issues:
WARNINGS:
accounts.DCIProfile.roles: (fields.W340) null has no effect on
ManyToManyField.
Operations to perform:
Apply all migrations: gatekeeper
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.6/site-
packages/django/core/management/__init__.py", line 371, in
execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.6/site-
packages/django/core/management/__init__.py", line 365, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.6/site-
packages/django/core/management/base.py", line 288, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python3.6/site-
packages/django/core/management/base.py", line 335, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python3.6/site-
packages/django/core/management/commands/migrate.py", line 159, in handle
pre_migrate_state =
executor._create_project_state(with_applied_migrations=True)
File "/usr/local/lib/python3.6/site-
packages/django/db/migrations/executor.py", line 79, in
_create_project_state
migration.mutate_state(state, preserve=False)
File "/usr/local/lib/python3.6/site-
packages/django/db/migrations/migration.py", line 85, in mutate_state
operation.state_forwards(self.app_label, new_state)
File "/usr/local/lib/python3.6/site-
packages/django/db/migrations/operations/fields.py", line 70, in
state_forwards
state.models[app_label,
self.model_name_lower].fields.append((self.name, field))
KeyError: ('exams', 'examquestion')
}}}
That led me to [https://stackoverflow.com/questions/34883026/django-
migrations-error-keyerror-list-uuser a Stack Overflow answer], and
especially kagronick's answer:
{{{
I found what causes this and the solution for it. If you have a squashed
migration that has a "replaces" property, remove the tuples that reference
migrations that don't appear in your django_migrations table. This fixes
it.
}}}
So, I made one change to the migration file:
{{{
diff --git a/exams/migrations/0001_squashed_0002_auto_20170519_2125.py
b/exams/migrations/0001_squashed_0002_auto_20170519_2125.py
index 0dd64a8a..1eac171d 100644
--- a/exams/migrations/0001_squashed_0002_auto_20170519_2125.py
+++ b/exams/migrations/0001_squashed_0002_auto_20170519_2125.py
@@ -7,7 +7,7 @@ from django.conf import settings
class Migration(migrations.Migration):
- replaces = [(b'exams', '0001_squashed_0002_auto_20170518_1851'),
(b'exams', '0002_auto_20170519_2125')]
+ replaces = []
}}}
And now the migration is successful:
{{{
root@ubuntu-xenial:/dcif# python3 manage.py migrate gatekeeper
System check identified some issues:
WARNINGS:
accounts.DCIProfile.roles: (fields.W340) null has no effect on
ManyToManyField.
Operations to perform:
Apply all migrations: gatekeeper
Running migrations:
Applying gatekeeper.0007_roleconstraint_invert... OK
}}}
I don't know exactly what the cause is here, but I feel like at minimum
this shouldn't fail quite so spectacularly. If the issue is really as
simple as Django failing to parse a migration file that "replaces" another
migration file, which has since been removed from the repository, I would
think that would be a bug.
--
Ticket URL: <https://code.djangoproject.com/ticket/29149>
Django <https://code.djangoproject.com/>
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