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
29124	Generated migration orders RemoveField and AlterUniqueTogether incorrectly, causing FieldDoesNotExist	Ed Morley	nobody	"Removing a field and its corresponding `unique_together` entry results in a `FieldDoesNotExist` exception when creating/applying the migration. 

This affects Django master + v1.11.10, and both the SQLite and MySQL backends (others not tested).

(See also #29123 which also only reproduces when `unique_together` is used)

== STR:
1. Git clone [https://github.com/edmorley/django-migration-remove-field-testcase https://github.com/edmorley/django-migration-remove-field-testcase]
2. `pip install https://github.com/django/django/archive/master.zip`
3. `./manage.py migrate`
4. `cp testapp/models_new.py testapp/models.py`
5. `./manage.py makemigrations --name broken_migration`
6. `./manage.py migrate`

== Expected:

New migration is created/applied successfully, which converts from the [https://github.com/edmorley/django-migration-remove-field-testcase/blob/master/testapp/models.py original model] to the [https://github.com/edmorley/django-migration-remove-field-testcase/blob/master/testapp/models_new.py new model].

== Actual:

The new `0002_broken_migration.py` migration incorrectly lists the `RemoveField` operation before the `AlterUniqueTogether` operation...

{{{#!python
    operations = [
        migrations.RemoveField(
            model_name='push',
            name='foo',
        ),
        migrations.AlterUniqueTogether(
            name='push',
            unique_together={('repository', 'revision')},
        ),
    ]
}}}

Which results in an exception at step 6...

{{{#!bash
$ ./manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions, testapp
Running migrations:
  Applying testapp.0002_broken_migration...Traceback (most recent call last):
  File "".../site-packages/django/db/models/options.py"", line 564, in get_field
    return self.fields_map[field_name]
KeyError: 'foo'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  ...
  File "".../site-packages/django/db/backends/base/schema.py"", line 286, in create_model
    columns = [model._meta.get_field(field).column for field in fields]
  File "".../site-packages/django/db/backends/base/schema.py"", line 286, in <listcomp>
    columns = [model._meta.get_field(field).column for field in fields]
  File "".../site-packages/django/db/models/options.py"", line 566, in get_field
    raise FieldDoesNotExist(""%s has no field named '%s'"" % (self.object_name, field_name))
django.core.exceptions.FieldDoesNotExist: Push has no field named 'foo'
}}}

== Additional notes:
* If the `('repository', 'revision')` entry in `unique_together` is omitted from both the original and new models, then the bug does not occur.
* This affects both the SQLite backend and the MySQL backend (others not tested).
* At time of testing, django master was at revision `6d794fb76212bb8a62fe2cd97cff173054e1c626`.
* The above was using Python 3.6.2."	Bug	closed	Migrations	dev	Normal	duplicate			Unreviewed	0	0	0	0	0	0