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
27915	Defining Index object in Meta.indexes in abstract class causes failure during migration of sub-classes	Tommy Beadle	Tim Graham	"If I define an abstract model like this:

{{{#!python
class AbstractClass(models.Model):
    text = models.TextField()
    class Meta:
        abstract=True
        indexes = [
            models.indexes.Index(fields=['text']),
        ]
}}}

and then subclass it:

{{{#!python
class NewClass1(AbstractClass):
    pass

class NewClass2(AbstractClass):
    pass
}}}

Then, when I make the migrations, an index with the same ID is created for the sub-classes:

{{{
(venv) $ ./manage.py makemigrations myapp
Migrations for 'myapp':
  myapp/migrations/0001_initial.py
    - Create model NewClass1
    - Create model NewClass2
    - Create index myapp_abstr_text_5dfb11_idx on field(s) text of model newclass2
    - Create index myapp_abstr_text_5dfb11_idx on field(s) text of model newclass1
}}}

which then results in the following traceback when performing the migration:

{{{
(venv) $ ./manage.py migrate
<snip>
Traceback (most recent call last):                                        
  File ""./manage.py"", line 22, in <module>
    execute_from_command_line(sys.argv)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/core/management/__init__.py"", line 363, in execute_from_command_line
    utility.execute()
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/core/management/__init__.py"", line 355, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/core/management/base.py"", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/core/management/base.py"", line 330, in execute
    output = self.handle(*args, **options)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/core/management/commands/migrate.py"", line 204, in handle 
    fake_initial=fake_initial,
  File ""/home/tbeadle/venv/lib/python3.6/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 ""/home/tbeadle/venv/lib/python3.6/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 ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/migrations/executor.py"", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/migrations/migration.py"", line 129, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/migrations/operations/models.py"", line 785, in database_forwards
    schema_editor.add_index(model, self.index)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/backends/base/schema.py"", line 330, in add_index
    self.execute(index.create_sql(model, self))
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/backends/base/schema.py"", line 119, in execute
    cursor.execute(sql, params)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/backends/utils.py"", line 80, in execute 
    return super(CursorDebugWrapper, self).execute(sql, params)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/backends/utils.py"", line 65, in execute 
    return self.cursor.execute(sql, params)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/utils.py"", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/utils/six.py"", line 685, in reraise
    raise value.with_traceback(tb)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/backends/utils.py"", line 65, in execute 
    return self.cursor.execute(sql, params)
  File ""/home/tbeadle/venv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py"", line 328, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: index myapp_abstr_text_5dfb11_idx already exists
}}}

This is apparently because the Index object gets created during creation of the abstract class and reused in the subclasses.  Instead, the name needs to be generated when it gets copied to the sub-classes."	Bug	closed	Database layer (models, ORM)	1.11	Release blocker	fixed			Accepted	1	0	0	0	0	0