#24424: Removing a model's last field results in SQL syntax error on SQLite
----------------------------+------------------------------------
Reporter: adnam | Owner: adnam
Type: Bug | Status: assigned
Component: Migrations | Version: 1.7
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 1
Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
----------------------------+------------------------------------
Comment (by MarkusH):
Initial models and migration:
{{{#!python
# models.py
from django.db import models
class Thing(models.Model):
pass
class Blob(Thing):
pass
# 0001_initial.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import migrations, models
class Migration(migrations.Migration):
dependencies = [
]
operations = [
migrations.CreateModel(
name='Thing',
fields=[
('id', models.AutoField(auto_created=True,
primary_key=True, serialize=False, verbose_name='ID')),
],
),
migrations.CreateModel(
name='Blob',
fields=[
('thing_ptr', models.OneToOneField(auto_created=True,
parent_link=True, primary_key=True, serialize=False, to='app_a.Thing')),
],
bases=('app_a.thing',),
),
]
}}}
Making `Thing` inherit a new model `Bar`:
{{{#!python
# models.py
from django.db import models
class Bar(models.Model):
pass
class Thing(Bar):
pass
class Blob(Thing):
pass
# 0002_auto.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import migrations, models
class Migration(migrations.Migration):
dependencies = [
('app_a', '0001_initial'),
]
operations = [
migrations.CreateModel(
name='Bar',
fields=[
('id', models.AutoField(auto_created=True,
primary_key=True, serialize=False, verbose_name='ID')),
],
),
migrations.RemoveField(
model_name='thing',
name='id',
),
migrations.AddField(
model_name='thing',
name='bar_ptr',
field=models.OneToOneField(auto_created=True, default=0,
parent_link=True, primary_key=True, serialize=False, to='app_a.Bar'),
preserve_default=False,
),
]
}}}
{{{
Operations to perform:
Target specific migration: 0002_auto_20150307_1707, from app_a
Running migrations:
Rendering model states... DONE
Applying app_a.0002_auto_20150307_1707...
('CREATE TABLE `app_a_bar` (`id` integer AUTO_INCREMENT NOT NULL PRIMARY
KEY)', None)
('SELECT engine FROM information_schema.tables WHERE table_name = %s',
['app_a_bar'])
('ALTER TABLE `app_a_thing` DROP COLUMN `id` CASCADE', [])
Traceback (most recent call last):
File "/home/markus/Coding/django/django/db/backends/utils.py", line 64,
in execute
return self.cursor.execute(sql, params)
File "/home/markus/Coding/django/django/db/backends/mysql/base.py", line
125, in execute
return self.cursor.execute(query, args)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 219, in execute
self.errorhandler(self, exc, value)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/connections.py", line 38, in defaulterrorhandler
raise errorvalue
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 205, in execute
r = self._query(query)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 372, in _query
rowcount = self._do_query(q)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 336, in _do_query
db.query(q)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/connections.py", line 282, in query
_mysql.connection.query(self, query)
_mysql_exceptions.OperationalError: (1090, "You can't delete all columns
with ALTER TABLE; use DROP TABLE instead")
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/markus/Coding/django/django/core/management/__init__.py",
line 330, in execute_from_command_line
utility.execute()
File "/home/markus/Coding/django/django/core/management/__init__.py",
line 322, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/markus/Coding/django/django/core/management/base.py", line
347, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/markus/Coding/django/django/core/management/base.py", line
398, in execute
output = self.handle(*args, **options)
File
"/home/markus/Coding/django/django/core/management/commands/migrate.py",
line 195, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/home/markus/Coding/django/django/db/migrations/executor.py", line
94, in migrate
self.apply_migration(states[migration], migration, fake=fake,
fake_initial=fake_initial)
File "/home/markus/Coding/django/django/db/migrations/executor.py", line
131, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/markus/Coding/django/django/db/migrations/migration.py",
line 111, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File
"/home/markus/Coding/django/django/db/migrations/operations/fields.py",
line 121, in database_forwards
schema_editor.remove_field(from_model,
from_model._meta.get_field(self.name))
File "/home/markus/Coding/django/django/db/backends/base/schema.py",
line 441, in remove_field
self.execute(sql)
File "/home/markus/Coding/django/django/db/backends/base/schema.py",
line 107, in execute
cursor.execute(sql, params)
File "/home/markus/Coding/django/django/db/backends/utils.py", line 79,
in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/markus/Coding/django/django/db/backends/utils.py", line 64,
in execute
return self.cursor.execute(sql, params)
File "/home/markus/Coding/django/django/db/utils.py", line 95, in
__exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/markus/Coding/django/django/utils/six.py", line 658, in
reraise
raise value.with_traceback(tb)
File "/home/markus/Coding/django/django/db/backends/utils.py", line 64,
in execute
return self.cursor.execute(sql, params)
File "/home/markus/Coding/django/django/db/backends/mysql/base.py", line
125, in execute
return self.cursor.execute(query, args)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 219, in execute
self.errorhandler(self, exc, value)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/connections.py", line 38, in defaulterrorhandler
raise errorvalue
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 205, in execute
r = self._query(query)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 372, in _query
rowcount = self._do_query(q)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/cursors.py", line 336, in _do_query
db.query(q)
File "/home/markus/.venvs/django-dev-py3/lib/python3.4/site-
packages/MySQLdb/connections.py", line 282, in query
_mysql.connection.query(self, query)
django.db.utils.OperationalError: (1090, "You can't delete all columns
with ALTER TABLE; use DROP TABLE instead")
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/24424#comment:12>
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