Django: RuntimeError: Model class test_django.apps.app1.models.xxx doesn’t declare an explicit app_label and isn’t in an application in INSTALLED_APPS.

1.Django项目错误提示：

RuntimeError: Model class xxx.apps.users.models.User doesn’t declare an explicit app_label and isn’t in an application in INSTALLED_APPS.

2. 项目结构：

django_project
    ├── LICENSE
    ├── main.py
    └── test_django
        ├── manage.py
        └── test_django
            ├── apps
            │   ├── app1
            │   │   ├── admin.py
            │   │   ├── apps.py
            │   │   ├── __init__.py
            │   │   ├── models.py
            │   │   ├── tests.py
            │   │   ├── urls.py
            │   │   └── views.py
            │   └── app2
            │       ├── admin.py
            │       ├── apps.py
            │       ├── __init__.py
            │       ├── models.py
            │       ├── tests.py
            │       ├── urls.py
            │       └── views.py
            ├── asgi.py
            ├── __init__.py
            ├── settings
            │   ├── dev.py
            │   └── prod.py
            ├── urls.py
            └── wsgi.py

2.解决

1. app内，使用相对路径引用Models模块：

# 在apps.app1.urls.py中导入apps.app1.views.py
from . import views

# 在apps.app1.views.py中导入apps.app1.models.py中的xxx
from .models import xxx

2. 不同app之间，使用以apps为根目录的绝对路径：

# 在apps.app2.views.py中导入apps.app1.models.py中的xxx
from app1.models import xxx

3. 其它参考

https://stackoverflow.com/questions/35388637/runtimeerror-model-class-django-contrib-sites-models-site-doesnt-declare-an-ex