makemigrations crashes with "'SpatialRefSysMixin' has no attribute '_meta'" on PostGIS

[Satish V Madala]

Am Using postgis as a backend and makemigrations threw back the error:

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/home/satish/work/django/django/core/management/__init__.py", line 366, in execute_from_command_line
    utility.execute()
  File "/home/satish/work/django/django/core/management/__init__.py", line 358, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/satish/work/django/django/core/management/base.py", line 294, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/satish/work/django/django/core/management/base.py", line 345, in execute
    output = self.handle(*args, **options)
  File "/home/satish/work/django/django/core/management/commands/makemigrations.py", line 173, in handle
    migration_name=self.migration_name,
  File "/home/satish/work/django/django/db/migrations/autodetector.py", line 47, in changes
    changes = self._detect_changes(convert_apps, graph)
  File "/home/satish/work/django/django/db/migrations/autodetector.py", line 198, in _detect_changes
    self._optimize_migrations()
  File "/home/satish/work/django/django/db/migrations/autodetector.py", line 362, in _optimize_migrations
    migration.operations = MigrationOptimizer().optimize(migration.operations, app_label=app_label)
  File "/home/satish/work/django/django/db/migrations/optimizer.py", line 38, in optimize
    result = self.optimize_inner(operations, app_label)
  File "/home/satish/work/django/django/db/migrations/optimizer.py", line 53, in optimize_inner
    result = operation.reduce(other, in_between, app_label)
  File "/home/satish/work/django/django/db/migrations/operations/models.py", line 213, in reduce
    return super(CreateModel, self).reduce(operation, in_between, app_label=app_label)
  File "/home/satish/work/django/django/db/migrations/operations/models.py", line 39, in reduce
    not operation.references_model(self.name, app_label)
  File "/home/satish/work/django/django/db/migrations/operations/models.py", line 119, in references_model
    model_app_label, model_name = self.model_to_key(model)
  File "/home/satish/work/django/django/db/migrations/operations/models.py", line 133, in model_to_key
    return model._meta.app_label, model._meta.object_name
AttributeError: type object 'SpatialRefSysMixin' has no attribute '_meta'

Is GeoDjango not ready for 1.11 dev version yet?

[Tim Graham]

Bisected the regression to 7fc4c1db627807874966e4f96b34cff7c9af886f. Steps to reproduce and a sample project are ​on django-users.

[Melvyn Sopacua]

Reproduction steps posted on mailing list:

1. Create a python3 virtualenv and activate it
2. pip install git+https://github.com/django/django.git
3. pip install psycopg2
4. django-admin startproject projectname
5. Add 'django.contrib.gis' to INSTALLED_APPS
6. Change the db backend to postgis in settings file
7. python manage.py makemigrations

[Melvyn Sopacua]

If above steps are accurate, then please verify if adding 'django.contrib.gis' to INSTALLED_APPS (which you haven't done in above steps) resolves the issue. The ​documentation on this is ambiguous. It suggests one can start the dev server without this step (and probably can), but the GeoDjango framework is improperly configured at that time.

[Satish V Madala]

I've missed documenting the step, I've added 'django.contrib.gis' to INSTALLED_APPS. Issue is same.

Replying to melvyn-sopacua:

If above steps are accurate, then please verify if adding 'django.contrib.gis' to INSTALLED_APPS (which you haven't done in above steps) resolves the issue. The ​documentation on this is ambiguous. It suggests one can start the dev server without this step (and probably can), but the GeoDjango framework is improperly configured at that time.

[Satish V Madala]

Hi,

Is there a patch for this bug?

Thanks.

[Simon Charette]

Not so far but it should be only a matter of adjusting ​this line to also check for isinstance(base, models.base.ModelBase).

[Tim Graham]

​PR

[GitHub <noreply@…>]

In a44fc00:

Fixed #27217 -- Fixed crash in CreateModel optimization with models that use mixins.

Thanks Simon Charette for review.