Django - AppRegistryNotReady("Models aren't loaded yet.") using cities

I have installed the cities_light library in Django and populated the db with the cities as instructed in the docs. I added the app in INSTALLED_APPS and I have been able to pull the data in this simple view. All cities load as expected:

def index(request):
    cities = City.objects.all()
    context = {
        'cities': cities
    }
    return render(request,'templates/index.html',context)

However, I am trying to create a model which has City as a foreign key, but when I run the app or try to make the migrations I get 'django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.'.

from cities_light.admin import City
from django.db import models

class Home(models.Model):
    location = models.ForeignKey(City, on_delete=models.CASCADE)

I suspect I might need to override the model. Would that be the case?

CodePudding user response：

In settings.py file add below code at the end of file:

SOUTH_MIGRATION_MODULES = {
    'cities_light': 'cities_light.south_migrations',
}

I think you did not add above code in settings.py file that's why you got that error.

Data update

Finally, populate your database with command:

./manage.py cities_light

CodePudding user response：

The same error appears after adding the south migration modules. I already had the database populated and I used it successfully for my view. Here is the settings.py content:

from pathlib import Path

BASE_DIR = Path(__file__).resolve().parent.parent

SECRET_KEY = 'django-insecure-n=_c6^ui9$e&t jsy(&eewc%n1rux91z3f94jwrwrq91w7^c43'

DEBUG = True

ALLOWED_HOSTS = []

INSTALLED_APPS = [
    'cities_light',

    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',

    'CBV_practice.web',
    'CBV_practice.auth_app',

]

CITIES_LIGHT_INCLUDE_COUNTRIES = ['BG']

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'CBV_practice.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [BASE_DIR / 'templates']
        ,
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'CBV_practice.wsgi.application'

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'cbv_practice_db_try_2',
        'USER': 'postgres-user',
        'PASSWORD': 'password',
        'HOST': '127.0.0.1',
        'PORT': '5432'
    }
}

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_TZ = True

STATIC_URL = 'static/'

DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

SOUTH_MIGRATION_MODULES = {
    'cities_light': 'cities_light.south_migrations',
}

The whole error:

Traceback (most recent call last):
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\manage.py", line 22, in <module>
    main()
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\core\management\__init__.py", line 446, in execute_from_command_line
    utility.execute()
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\core\management\__init__.py", line 420, in execute
    django.setup()
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\apps\registry.py", line 116, in populate
    app_config.import_models()
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\apps\config.py", line 269, in import_models
    self.models_module = import_module(models_module_name)
  File "C:\Users\marti\AppData\Local\Programs\Python\Python39\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\CBV_practice\web\models.py", line 1, in <module>
    from cities_light.admin import City
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\cities_light\admin.py", line 7, in <module>
    from . import forms
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\cities_light\forms.py", line 5, in <module>
    Country, Region, SubRegion, City = get_cities_models()
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\cities_light\loading.py", line 17, in get_cities_models
    return [get_cities_model(model_name) for model_name in model_names]
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\cities_light\loading.py", line 17, in <listcomp>
    return [get_cities_model(model_name) for model_name in model_names]
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\cities_light\loading.py", line 12, in get_cities_model
    return get_model(CITIES_LIGHT_APP_NAME, model_name, *args, **kwargs)
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\apps\registry.py", line 201, in get_model
    self.check_models_ready()
  File "C:\Users\marti\PycharmProjects\WebDevelopmentCourseDjango\WEB FRAMEWORK\CBV_practice\venv\lib\site-packages\django\apps\registry.py", line 143, in check_models_ready
    raise AppRegistryNotReady("Models aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.