#27940: Migrations fail when when Models parent class is changed to abstract --
Wrong SQL being generated
-------------------------------------+-------------------------------------
Reporter: Sawan | Owner: nobody
Vithlani |
Type: Bug | Status: new
Component: | Version: 1.10
Migrations | Keywords: SQLite migrations
Severity: Normal | abstract inheritance
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Consider the following class hierarchy:
{{{
#!python
class TestCase(models.Model):
name = models.CharField(max_length=10)
class TerminalTest(TestCase):
pass
class BrowserTest(TestCase):
pass
$ ./manage.py makemigrations testbed
Migrations for 'testbed':
testbed\migrations\0001_initial.py:
- Create model TestCase
- Create model BrowserTest
- Create model TerminalTest
$ ./manage.py migrate testbed
Operations to perform:
Apply all migrations: testbed
Running migrations:
Applying testbed.0001_initial... OK
}}}
Now we want to make the parent an abstract class:
{{{
#!python
class TestCase(models.Model):
name = models.CharField(max_length=10)
class Meta:
abstract = True
class TerminalTest(TestCase):
pass
class BrowserTest(TestCase):
pass
$ ./manage.py migrate testbed
Operations to perform:
Apply all migrations: testbed
Running migrations:
Applying testbed.0002_auto_20170315_1600...Traceback (most recent call
last):
File "C:\my-venv\lib\site-packages\django\db\backends\utils.py", line
64, in execute
return self.cursor.execute(sql, params)
File "C:\my-venv\lib\site-packages\django\db\backends\sqlite3\base.py",
line 337, in execute
return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: near ")": syntax error
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 "C:\my-venv\lib\site-packages\django\core\management\__init__.py",
line 367, in execute_from_command_line
utility.execute()
File "C:\my-venv\lib\site-packages\django\core\management\__init__.py",
line 359, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\my-venv\lib\site-packages\django\core\management\base.py", line
294, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\my-venv\lib\site-packages\django\core\management\base.py", line
345, in execute
output = self.handle(*args, **options)
File "C:\my-venv\lib\site-
packages\django\core\management\commands\migrate.py", line 204, in handle
fake_initial=fake_initial,
File "C:\my-venv\lib\site-packages\django\db\migrations\executor.py",
line 115, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake,
fake_initial=fake_initial)
File "C:\my-venv\lib\site-packages\django\db\migrations\executor.py",
line 145, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake,
fake_initial=fake_initial)
File "C:\my-venv\lib\site-packages\django\db\migrations\executor.py",
line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "C:\my-venv\lib\site-packages\django\db\migrations\migration.py",
line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File "C:\my-venv\lib\site-
packages\django\db\migrations\operations\fields.py", line 147, in
database_forwards
schema_editor.remove_field(from_model,
from_model._meta.get_field(self.name))
File "C:\my-venv\lib\site-
packages\django\db\backends\sqlite3\schema.py", line 249, in remove_field
self._remake_table(model, delete_fields=[field])
File "C:\my-venv\lib\site-
packages\django\db\backends\sqlite3\schema.py", line 199, in _remake_table
self.quote_name(model._meta.db_table),
File "C:\my-venv\lib\site-packages\django\db\backends\base\schema.py",
line 112, in execute
cursor.execute(sql, params)
File "C:\my-venv\lib\site-packages\django\db\backends\utils.py", line
79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "C:\my-venv\lib\site-packages\django\db\backends\utils.py", line
64, in execute
return self.cursor.execute(sql, params)
File "C:\my-venv\lib\site-packages\django\db\utils.py", line 94, in
__exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "C:\my-venv\lib\site-packages\django\utils\six.py", line 685, in
reraise
raise value.with_traceback(tb)
File "C:\my-venv\lib\site-packages\django\db\backends\utils.py", line
64, in execute
return self.cursor.execute(sql, params)
File "C:\my-venv\lib\site-packages\django\db\backends\sqlite3\base.py",
line 337, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: near ")": syntax error
}}}
The problem is that the SQL query generated by this
([https://github.com/django/django/blob/320ec4ed27c254a87e09a70601b1b27ae0a0456e/django/db/backends/sqlite3/schema.py#L195-L198
code block]) in ''**django/db/backends/sqlite3/schema.py**'':
{{{#!python
# Copy data from the old table into the new table
field_maps = list(mapping.items())
self.execute("INSERT INTO %s (%s) SELECT %s FROM %s" % (
self.quote_name(temp_model._meta.db_table),
', '.join(self.quote_name(x) for x, y in field_maps),
', '.join(y for x, y in field_maps),
self.quote_name(model._meta.db_table),
))
}}}
reads:
{{{#!sql
'INSERT INTO "testbed_browsertest" () SELECT FROM
"testbed_browsertest__old" '
}}}
This is a wrong query in SQLite syntax. Correct query is:
{{{#!sql
'INSERT INTO "testbed_browsertest" SELECT * FROM
"testbed_browsertest__old" '
}}}
This has been verified by monkey-patching the query generated and having
the migration succeed.
--
Ticket URL: <https://code.djangoproject.com/ticket/27940>
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