Django 1.9 deprecation warnings app_label

Question

I've just updated to Django v1.8, and testing my local setup before updating my project and I've had a deprecation warning that I've never seen before, nor does it make any sense to me. I may be just overlooking something or misunderstanding the documentation.

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:6: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Difficulty doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Difficulty(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:21: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Zone doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Zone(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:49: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Boss doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Boss(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:79: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Item doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Item(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:14: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Category doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Category(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:36: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Comment doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Comment(ScoreMixin, ProfileMixin, models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:64: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Forum doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Forum(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:88: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Post doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Post(ScoreMixin, ProfileMixin, models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:119: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.CommentPoint doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class CommentPoint(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:127: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.TopicPoint doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class TopicPoint(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/auctionhouse/models.py:10: RemovedInDjango19Warning: Model class ankylosguild.apps.auctionhouse.models.Auction doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Auction(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/auctionhouse/models.py:83: RemovedInDjango19Warning: Model class ankylosguild.apps.auctionhouse.models.Bid doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Bid(models.Model):

Now this poses 3 questions for me.

1. According to the documentation, Options.app_label isn't a requirement unless the model is outside of the application module, which in my case, it isn't. Secondly, this behaviour was deprecated in 1.7 anyway, so why is it even an issue?
2. The applications are all in the INSTALLED_APPS tuple, so it surely can't be that?
3. Why would the applications not be loaded before they are called if everything is in the INSTALLED_APPS tuple?

If I am indeed doing something wrong, what is the correct way of doing it as the docs don't really clear up what is causing this problem or how to rectify it.

Answer 1

As stated in the warning, this happens either :

• When you're using a model which is not in an INSTALLED_APPS;
• Or when you're using a model before its application is loaded.

Since you did refer the app in the INSTALLED_APPS setting, this is most likely you're using a model before the app initialisation.

Typically, this occurs when you have from .models import SomeModels in an apps.py early signal (for example post_migrate). Instead of referring your models the classic way here, it is recommended to use AppConfig.get_model(). Check your apps.py file for any model import, and replace them using this api.

For example instead of :

# apps.py

from django.apps import AppConfig
from .models import MyModel

def do_stuff(sender, **kwargs):
    MyModel.objects.get() # etc...

class MyAppConfig(AppConfig):
    name = 'src.my_app_label'

    def ready(self):
        post_migrate.connect(do_stuff, sender=self)

Do this :

# apps.py

from django.apps import AppConfig

def do_stuff(sender, **kwargs):
    mymodel = sender.get_model('MyModel')
    mymodel.objects.get() # etc...

class MyAppConfig(AppConfig):
    name = 'src.my_app_label'

    def ready(self):
        post_migrate.connect(do_stuff, sender=self)

Note this enforcement was introduced in bug #21719.