id summary reporter owner description type status component version severity resolution keywords cc stage has_patch needs_docs needs_tests needs_better_patch easy ui_ux 33185 sqlmigrate crashes given a RenameModel operation with a self-referencing foreign key on MySQL Jacob Walls "A migration that renames a table having a self-referencing foreign key will migrate just fine but crashes when using `sqlmigrate` to inspect SQL statements beforehand. I tested on MySQL 5.7.31. 1. fresh project `selfapp` 2. models.py --> {{{ class Employee(models.Model): manager = models.ForeignKey('self', on_delete=models.SET_NULL, null=True) }}} 3. `python manage.py makemigrations` 4. `python manage.py migrate` 5. models.py --> {{{ class RenamedEmployee(models.Model): manager = models.ForeignKey('self', on_delete=models.SET_NULL, null=True) }}} 6. `python manage.py makemigrations` answer prompt `Was the model selfapp.Employee renamed to RenamedEmployee? [y/N] ` with Y -- resulting migration: -- {{{ # Generated by Django 4.1.dev20211008135104 on 2021-10-10 16:11 from django.db import migrations class Migration(migrations.Migration): dependencies = [ ('selfapp', '0001_initial'), ] operations = [ migrations.RenameModel( old_name='Employee', new_name='RenamedEmployee', ), ] }}} 7. `python manage.py sqlmigrate selfapp 0002` {{{ Traceback (most recent call last): File ""/Users/jwalls/django/django/db/backends/utils.py"", line 82, in _execute return self.cursor.execute(sql) File ""/Users/jwalls/django/django/db/backends/mysql/base.py"", line 73, in execute return self.cursor.execute(query, args) File ""/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/MySQLdb/cursors.py"", line 206, in execute res = self._query(query) File ""/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/MySQLdb/cursors.py"", line 319, in _query db.query(q) File ""/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/MySQLdb/connections.py"", line 259, in query _mysql.connection.query(self, query) MySQLdb._exceptions.ProgrammingError: (1146, ""Table 'mydatabase.selfapp_renamedemployee' doesn't exist"") The above exception was the direct cause of the following exception: Traceback (most recent call last): File ""/Users/jwalls/self/manage.py"", line 22, in main() File ""/Users/jwalls/self/manage.py"", line 18, in main execute_from_command_line(sys.argv) File ""/Users/jwalls/django/django/core/management/__init__.py"", line 419, in execute_from_command_line utility.execute() File ""/Users/jwalls/django/django/core/management/__init__.py"", line 413, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File ""/Users/jwalls/django/django/core/management/base.py"", line 363, in run_from_argv self.execute(*args, **cmd_options) File ""/Users/jwalls/django/django/core/management/commands/sqlmigrate.py"", line 29, in execute return super().execute(*args, **options) File ""/Users/jwalls/django/django/core/management/base.py"", line 407, in execute output = self.handle(*args, **options) File ""/Users/jwalls/django/django/core/management/commands/sqlmigrate.py"", line 65, in handle sql_statements = loader.collect_sql(plan) File ""/Users/jwalls/django/django/db/migrations/loader.py"", line 352, in collect_sql state = migration.apply(state, schema_editor, collect_sql=True) File ""/Users/jwalls/django/django/db/migrations/migration.py"", line 125, in apply operation.database_forwards(self.app_label, schema_editor, old_state, project_state) File ""/Users/jwalls/django/django/db/migrations/operations/models.py"", line 343, in database_forwards schema_editor.alter_field( File ""/Users/jwalls/django/django/db/backends/base/schema.py"", line 618, in alter_field self._alter_field(model, old_field, new_field, old_type, new_type, File ""/Users/jwalls/django/django/db/backends/base/schema.py"", line 631, in _alter_field fk_names = self._constraint_names(model, [old_field.column], foreign_key=True) File ""/Users/jwalls/django/django/db/backends/base/schema.py"", line 1344, in _constraint_names constraints = self.connection.introspection.get_constraints(cursor, model._meta.db_table) File ""/Users/jwalls/django/django/db/backends/mysql/introspection.py"", line 287, in get_constraints cursor.execute(""SHOW INDEX FROM %s"" % self.connection.ops.quote_name(table_name)) File ""/Users/jwalls/django/django/db/backends/utils.py"", line 98, in execute return super().execute(sql, params) File ""/Users/jwalls/django/django/db/backends/utils.py"", line 66, in execute return self._execute_with_wrappers(sql, params, many=False, executor=self._execute) File ""/Users/jwalls/django/django/db/backends/utils.py"", line 75, in _execute_with_wrappers return executor(sql, params, many, context) File ""/Users/jwalls/django/django/db/backends/utils.py"", line 84, in _execute return self.cursor.execute(sql, params) File ""/Users/jwalls/django/django/db/utils.py"", line 90, in __exit__ raise dj_exc_value.with_traceback(traceback) from exc_value File ""/Users/jwalls/django/django/db/backends/utils.py"", line 82, in _execute return self.cursor.execute(sql) File ""/Users/jwalls/django/django/db/backends/mysql/base.py"", line 73, in execute return self.cursor.execute(query, args) File ""/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/MySQLdb/cursors.py"", line 206, in execute res = self._query(query) File ""/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/MySQLdb/cursors.py"", line 319, in _query db.query(q) File ""/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/MySQLdb/connections.py"", line 259, in query _mysql.connection.query(self, query) django.db.utils.ProgrammingError: (1146, ""Table 'mydatabase.selfapp_renamedemployee' doesn't exist"") }}} 8. `python manage.py migrate` works fine: {{{ Operations to perform: Apply all migrations: admin, auth, contenttypes, selfapp, sessions Running migrations: Applying selfapp.0002_rename_employee_renamedemployee... OK }}} 9. And now `python manage.py sqlmigrate selfapp 0002` works, but I wanted to verify the safety of SQL (in a larger migration) before migrating: {{{ -- -- Rename model Employee to RenamedEmployee -- RENAME TABLE `selfapp_employee` TO `selfapp_renamedemployee`; ALTER TABLE `selfapp_renamedemployee` DROP FOREIGN KEY `selfapp_renamedemplo_manager_id_51e9d90c_fk_selfapp_r`; ALTER TABLE `selfapp_renamedemployee` ADD CONSTRAINT `selfapp_renamedemplo_manager_id_51e9d90c_fk_selfapp_r` FOREIGN KEY (`manager_id`) REFERENCES `selfapp_renamedemployee` (`id`); }}}" Bug new Migrations dev Normal Accepted 0 0 0 0 0 0