#27946: Removing unique_together creates invalid migration
-----------------------------------------+------------------------
Reporter: Robin Elvin | Owner: nobody
Type: Uncategorized | Status: new
Component: Migrations | Version: 1.8
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I had a model which had a unique_together constraint defined. Now I wish
to remove this so the unique_together was removed from the model and a
migration created. When applying the migration the following error
occurred:
{{{
Applying main.0091_auto_20170316_1046...Traceback (most recent call
last):
File "manage.py", line 8, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python2.7/site-
packages/django/core/management/__init__.py", line 354, in
execute_from_command_line
utility.execute()
File "/usr/local/lib/python2.7/site-
packages/django/core/management/__init__.py", line 346, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python2.7/site-
packages/django/core/management/base.py", line 394, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/local/lib/python2.7/site-
packages/django/core/management/base.py", line 445, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python2.7/site-
packages/django/core/management/commands/migrate.py", line 222, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/usr/local/lib/python2.7/site-
packages/django/db/migrations/executor.py", line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake,
fake_initial=fake_initial)
File "/usr/local/lib/python2.7/site-
packages/django/db/migrations/executor.py", line 148, in apply_migration
state = migration.apply(state, schema_editor)
File "/usr/local/lib/python2.7/site-
packages/django/db/migrations/migration.py", line 115, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File "/usr/local/lib/python2.7/site-
packages/django/db/migrations/operations/models.py", line 359, in
database_forwards
getattr(new_model._meta, self.option_name, set()),
File "/usr/local/lib/python2.7/site-
packages/django/db/backends/base/schema.py", line 320, in
alter_unique_together
self._delete_composed_index(model, fields, {'unique': True},
self.sql_delete_unique)
File "/usr/local/lib/python2.7/site-
packages/django/db/backends/mysql/schema.py", line 80, in
_delete_composed_index
return super(DatabaseSchemaEditor, self)._delete_composed_index(model,
fields, *args)
File "/usr/local/lib/python2.7/site-
packages/django/db/backends/base/schema.py", line 349, in
_delete_composed_index
", ".join(columns),
ValueError: Found wrong number (0) of constraints for
main_projectdrivefile(name, directory_id)
}}}
The model's Meta before starting which was subsequently removed prior to
creating the migration:
{{{
#!python
class Meta:
unique_together = ('name', 'directory')
}}}
The migration created looks like this:
{{{
#!python
class Migration(migrations.Migration):
dependencies = [
('main', '0090_auto_20170314_1033'),
]
operations = [
migrations.AlterUniqueTogether(
name='projectdrivefile',
unique_together=set([]),
),
]
}}}
Steps to reproduce:
1. Create a model with a unique_together constraint
2. Create a migration for this model with makemigrations
3. Apply migration
4. Remove unique_together completely
5. Create a migration for this model with makemigrations
6. Apply migration
--
Ticket URL: <https://code.djangoproject.com/ticket/27946>
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