Xiang Wang @ 2020-04-22 22:29:35
this bug has been posted at django ticket.
I met a problem when I convert a unique_together to the unique=True attribute.
- first commit, everything is ok
- I create a model file.
// testapp/models.py class MyModel(models.Model): name = models.CharField(max_length=32) class Meta: unique_together = ("name", )- the migrations file looks like this.
// testapp/migrations/0001_initial.py # Generated by Django 3.0.5 on 2020-04-22 12:47 from django.db import migrations, models class Migration(migrations.Migration): dependencies = [ ('testapp', '0001_initial'), ] operations = [ migrations.AlterField( model_name='mymodel', name='name', field=models.CharField(max_length=32, unique=True), ), migrations.AlterUniqueTogether( name='mymodel', unique_together=set(), ), ] - second commit: then I remove the
unique_togetherand addunique=Trueto the fieldMyModel.nameclass MyModel(models.Model): name = models.CharField(max_length=32, unique=True) class Meta: pass # unique_together = ("name", )class Migration(migrations.Migration): dependencies = [ ('testapp', '0001_initial'), ] operations = [ migrations.AlterField( model_name='mymodel', name='name', field=models.CharField(max_length=32, unique=True), ), migrations.AlterUniqueTogether( name='mymodel', unique_together=set(), ), ]
However, when I apply the migrations, an error occurs;
wangx@aliyun:~/testunique$ python3 manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, sessions, testapp
Running migrations:
Applying contenttypes.0001_initial... OK
Applying auth.0001_initial... OK
Applying admin.0001_initial... OK
Applying admin.0002_logentry_remove_auto_add... OK
Applying admin.0003_logentry_add_action_flag_choices... OK
Applying contenttypes.0002_remove_content_type_name... OK
Applying auth.0002_alter_permission_name_max_length... OK
Applying auth.0003_alter_user_email_max_length... OK
Applying auth.0004_alter_user_username_opts... OK
Applying auth.0005_alter_user_last_login_null... OK
Applying auth.0006_require_contenttypes_0002... OK
Applying auth.0007_alter_validators_add_error_messages... OK
Applying auth.0008_alter_user_username_max_length... OK
Applying auth.0009_alter_user_last_name_max_length... OK
Applying auth.0010_alter_group_name_max_length... OK
Applying auth.0011_update_proxy_permissions... OK
Applying sessions.0001_initial... OK
Applying testapp.0001_initial... OK
Applying testapp.0002_auto_20200422_1247...Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/utils.py", line 86, in _execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/mysql/base.py", line 74, in execute
return self.cursor.execute(query, args)
File "/usr/local/lib/python3.6/dist-packages/MySQLdb/cursors.py", line 209, in execute
res = self._query(query)
File "/usr/local/lib/python3.6/dist-packages/MySQLdb/cursors.py", line 315, in _query
db.query(q)
File "/usr/local/lib/python3.6/dist-packages/MySQLdb/connections.py", line 239, in query
_mysql.connection.query(self, query)
MySQLdb._exceptions.OperationalError: (1061, "Duplicate key name 'testapp_mymodel_name_ba5e2bd2_uniq'")
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "manage.py", line 21, in <module>
main()
File "manage.py", line 17, in main
execute_from_command_line(sys.argv)
File "/usr/local/lib/python3.6/dist-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
utility.execute()
File "/usr/local/lib/python3.6/dist-packages/django/core/management/__init__.py", line 395, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python3.6/dist-packages/django/core/management/base.py", line 328, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python3.6/dist-packages/django/core/management/base.py", line 369, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python3.6/dist-packages/django/core/management/base.py", line 83, in wrapped
res = handle_func(*args, **kwargs)
File "/usr/local/lib/python3.6/dist-packages/django/core/management/commands/migrate.py", line 233, in handle
fake_initial=fake_initial,
File "/usr/local/lib/python3.6/dist-packages/django/db/migrations/executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python3.6/dist-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python3.6/dist-packages/django/db/migrations/executor.py", line 245, in apply_migration
state = migration.apply(state, schema_editor)
File "/usr/local/lib/python3.6/dist-packages/django/db/migrations/migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/usr/local/lib/python3.6/dist-packages/django/db/migrations/operations/fields.py", line 249, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/base/schema.py", line 565, in alter_field
old_db_params, new_db_params, strict)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/base/schema.py", line 745, in _alter_field
self.execute(self._create_unique_sql(model, [new_field.column]))
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/base/schema.py", line 142, in execute
cursor.execute(sql, params)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/utils.py", line 100, in execute
return super().execute(sql, params)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/utils.py", line 86, in _execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python3.6/dist-packages/django/db/utils.py", line 90, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/utils.py", line 86, in _execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python3.6/dist-packages/django/db/backends/mysql/base.py", line 74, in execute
return self.cursor.execute(query, args)
File "/usr/local/lib/python3.6/dist-packages/MySQLdb/cursors.py", line 209, in execute
res = self._query(query)
File "/usr/local/lib/python3.6/dist-packages/MySQLdb/cursors.py", line 315, in _query
db.query(q)
File "/usr/local/lib/python3.6/dist-packages/MySQLdb/connections.py", line 239, in query
_mysql.connection.query(self, query)
django.db.utils.OperationalError: (1061, "Duplicate key name 'testapp_mymodel_name_ba5e2bd2_uniq'")
I check the sql for these migrations, it shows:
wangx@aliyun:~/testunique$ python3 manage.py sqlmigrate testapp 0001
--
-- Create model MyModel
--
CREATE TABLE `testapp_mymodel` (`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY, `name` varchar(32) NOT NULL);
ALTER TABLE `testapp_mymodel` ADD CONSTRAINT `testapp_mymodel_name_ba5e2bd2_uniq` UNIQUE (`name`);
wangx@aliyun:~/testunique$ python3 manage.py sqlmigrate testapp 0002
--
-- Alter field name on mymodel
--
ALTER TABLE `testapp_mymodel` ADD CONSTRAINT `testapp_mymodel_name_ba5e2bd2_uniq` UNIQUE (`name`);
--
-- Alter unique_together for mymodel (0 constraint(s))
--
ALTER TABLE `testapp_mymodel` DROP INDEX `testapp_mymodel_name_ba5e2bd2_uniq`;
it looks like django will
- first create the index for
unique=True - drop the index for
unique_together=('name', )
but the program for creating index name generates the same index name :testapp_mymodel_name_ba5e2bd2_uniq, so when django create the same index, Duplicate key name error occurs.