AppRegistryNotReady: Apps aren't loaded yet. Django

Question

I'm trying to run django 1.9 on google app engine. Got the below error when trying to access API's through Google API Explorer.

Traceback (most recent call last):
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 240, in Handle
    handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
    handler, path, err = LoadObject(self._handler)
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 96, in LoadObject
    __import__(cumulative_path)
  File "/home/gemini/projects/cityguide-backend/src/cityguide/api/services.py", line 9, in <module>
    from cityguide.api.internal.categories import Categories
  File "/home/gemini/projects/cityguide-backend/src/cityguide/api/internal/categories.py", line 10, in <module>
    from cityguide.models import Category
  File "/home/gemini/projects/cityguide-backend/src/cityguide/models.py", line 8, in <module>
    class ContactDetails(models.Model):
  File "/home/gemini/projects/cityguide-backend/src/lib/django/db/models/base.py", line 94, in __new__
    app_config = apps.get_containing_app_config(module)
  File "/home/gemini/projects/cityguide-backend/src/lib/django/apps/registry.py", line 239, in get_containing_app_config
    self.check_apps_ready()
  File "/home/gemini/projects/cityguide-backend/src/lib/django/apps/registry.py", line 124, in check_apps_ready
    raise AppRegistryNotReady("Apps aren't loaded yet.")
AppRegistryNotReady: Apps aren't loaded yet.

I already added

builtins:
- deferred: on
- remote_api: on
- django_wsgi: on

handlers:
 - url: .*
   script: mysite.wsgi.application

env_variables:
  DJANGO_SETTINGS_MODULE: 'mysite.settings'

inside app.yaml file.

wsgi.py looks like

import os

from django.core.wsgi import get_wsgi_application
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")

application = get_wsgi_application()

I tried adding django.setup() line on the top of models.py but it shows a different error.

ERROR    2016-02-01 10:03:02,918 wsgi.py:263] 
Traceback (most recent call last):
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 240, in Handle
    handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
    handler, path, err = LoadObject(self._handler)
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 96, in LoadObject
    __import__(cumulative_path)
  File "/home/gemini/projects/cityguide-backend/src/cityguide/api/services.py", line 9, in <module>
    from cityguide.api.internal.categories import Categories
  File "/home/gemini/projects/cityguide-backend/src/cityguide/api/internal/categories.py", line 10, in <module>
    from cityguide.models import Category
  File "/home/gemini/projects/cityguide-backend/src/cityguide/models.py", line 6, in <module>
    django.setup()
  File "/home/gemini/projects/cityguide-backend/src/lib/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/gemini/projects/cityguide-backend/src/lib/django/apps/registry.py", line 115, in populate
    app_config.ready()
  File "/home/gemini/projects/cityguide-backend/src/lib/django/contrib/admin/apps.py", line 22, in ready
    self.module.autodiscover()
  File "/home/gemini/projects/cityguide-backend/src/lib/django/contrib/admin/__init__.py", line 26, in autodiscover
    autodiscover_modules('admin', register_to=site)
  File "/home/gemini/projects/cityguide-backend/src/lib/django/utils/module_loading.py", line 50, in autodiscover_modules
    import_module('%s.%s' % (app_config.name, module_to_search))
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/home/gemini/projects/cityguide-backend/src/cityguide/admin.py", line 2, in <module>
    from cityguide.models import Category
ImportError: cannot import name Category
ERROR    2016-02-01 10:03:02,919 wsgi.py:263] 
Traceback (most recent call last):
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 240, in Handle
    handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
    handler, path, err = LoadObject(self._handler)
  File "/home/gemini/softwares/google_appengine/google/appengine/runtime/wsgi.py", line 96, in LoadObject
    __import__(cumulative_path)
  File "/home/gemini/projects/cityguide-backend/src/cityguide/api/services.py", line 9, in <module>
    from cityguide.api.internal.categories import Categories
  File "/home/gemini/projects/cityguide-backend/src/cityguide/api/internal/categories.py", line 10, in <module>
INFO     2016-02-01 10:03:03,000 module.py:794] default: "POST /_ah/spi/BackendService.getApiConfigs HTTP/1.1" 500 -
    from cityguide.models import Category
INFO     2016-02-01 10:03:03,001 module.py:794] default: "POST /_ah/spi/BackendService.getApiConfigs HTTP/1.1" 500 -
  File "/home/gemini/projects/cityguide-backend/src/cityguide/models.py", line 6, in <module>
INFO     2016-02-01 10:03:03,001 module.py:794] default: "GET /_ah/api/discovery/v1/apis HTTP/1.1" 500 60
    django.setup()
INFO     2016-02-01 10:03:03,001 module.py:794] default: "GET /_ah/api/discovery/v1/apis HTTP/1.1" 500 60
  File "/home/gemini/projects/cityguide-backend/src/lib/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/gemini/projects/cityguide-backend/src/lib/django/apps/registry.py", line 78, in populate
    raise RuntimeError("populate() isn't reentrant")
RuntimeError: populate() isn't reentrant

Temporary solution for this problem:

Seems like I need to open the home page first. So that it would loads the db since I made the homepage to return all the db table contents . Once the db lists shown on the home page, we are ready to call the Google API Explorer.

Is there any way to refine this solution?

Solution

You should first initiate django this way in your script:

import django
django.setup()

See https://docs.djangoproject.com/en/1.9/ref/applications/#django.setup

You can also look at the Troubleshooting section of the link to see other possibilities to solve this aprticular exception.

By adding the above two lines at the top of services.py file solves this problem for me..

Comments

[Håken Lid]

The error message usually means that application = get_wsgi_application() has not run. For instance if you import django models directly. I think there's some setup process needed to connect the python models to the database.

[Håken Lid]

I'm not sure what happens in this step File "/home/gemini/softwares/google_appengine/google/appengine/ru‌​ntime/wsgi.py", line 96, in LoadObject __import__(cumulative_path), but it must be a different wsgi.py from the one in the django project. Maybe get_wsgi_application() step hasn't run.

[Louis]

@AvinashRaj Does it work if you try running your site with Django's manage.py runserver?

[Avinash Raj]

@Louis no, it won't..

[Håken Lid]

It might have to be added to this file. /home/gemini/softwares/google_appengine/google/appengine/run‌​time/wsgi.py

[Avinash Raj]

@HåkenLid pls see my update.. I have added a temp solution.

[Håken Lid]

@AvinashRaj I can't suggest a better permanent solution. I've never used django with google app engine or the Google API explorer.