Django 在服务器启动时尝试导入模块失败（“看起来不像模块路径”）

Question

似乎我正在按照说明进行操作，但不知何故 Django 并没有将 django_countries 视为一个应用程序。

错误：

System check identified no issues (0 silenced).
February 18, 2021 - 23:56:01
Django version 3.1.4, using settings 'django_project.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/utils/module_loading.py", line 13, in import_string
    module_path, class_name = dotted_path.rsplit('.', 1)
ValueError: not enough values to unpack (expected 2, got 1)

The above exception was the direct cause of the following exception:
(WSGI stuff...)

settings.py：

INSTALLED_APPS = [
    'django_countries',
    'registration.apps.RegistrationConfig',
     .....

项目树：

.
├── db.sqlite3
├── django_project
│   ├── asgi.py
│   ├── __init__.py
│   ├── __pycache__
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
├── manage.py
├── myapp
│   ├── admin.py
│   ├── apps.py
│   ├── forms.py
│   ├── __init__.py
│   ├── migrations
│   ├── models.py
│   ├── __pycache__
│   ├── static
│   ├── templates
│   ├── tests.py
│   ├── urls.py
│   └── views.py
├── readme.rst
├── registration
│   ├── admin.py
│   ├── apps.py
│   ├── __init__.py
│   ├── migrations
│   ├── models.py
│   ├── __pycache__
│   ├── static
│   ├── templates
│   ├── tests.py
│   ├── urls.py
│   └── views.py
├── requirements.txt
├── static
│   └── project
├── templates
│   └── project.html
└── venv
    ├── bin
    ├── include
    ├── lib
    ├── lib64 -> lib
    └── pyvenv.cfg

我用 pip 安装了它，使用 virtualenv。我的虚拟机处于活动状态，我可以使用 pip 列表检查它，也可以使用我用来运行 django (python manage.py runserver) 的相同解释器导入 django-countries。无论如何，在 django 模型中，我可以清楚地导入和使用 django-countries (pycharm)。

怎么了？

Answer 1

我认为我真正应该做的是删除这个问题。但是，一个人必须承认自己的白痴，所以....

显然我最初是这样做的，但从未注意到：

MIDDLEWARE = [
    .... middlewares....
    'django_countries', ]

我收到了错误，因此认为这是一个 venv 问题并为此项目重新安装了我的虚拟环境。然后我正确地将其添加到已安装的应用程序中，而不是中间件部分：

INSTALLED_APPS = [
    'django_countries',
    'registration.apps.RegistrationConfig',
     .....

但由于 Django 导入中间件的过程仍在尝试导入绝对不是中间件的东西，并且该导入的语法错误，因此它在启动时失败并显示以下完整堆栈跟踪：

xception in thread django-main-thread:
Traceback (most recent call last):
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/utils/module_loading.py", line 15, in import_string
    module_path, class_name = dotted_path.rsplit('.', 1)
ValueError: not enough values to unpack (expected 2, got 1)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/servers/basehttp.py", line 45, in get_internal_wsgi_application
    return import_string(app_path)
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/utils/module_loading.py", line 19, in import_string
    module = import_module(module_path)
  File "/usr/lib/python3.9/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 "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/django_project/wsgi.py", line 16, in <module>
    application = get_wsgi_application()
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/wsgi.py", line 13, in get_wsgi_application
    return WSGIHandler()
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/handlers/wsgi.py", line 127, in __init__
    self.load_middleware()
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/handlers/base.py", line 40, in load_middleware
    middleware = import_string(middleware_path)
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/utils/module_loading.py", line 17, in import_string
    raise ImportError("%s doesn't look like a module path" % dotted_path) from err
ImportError: django_countries doesn't look like a module path

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/utils/autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 138, in inner_run
    handler = self.get_handler(*args, **options)
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/contrib/staticfiles/management/commands/runserver.py", line 27, in get_handler
    handler = super().get_handler(*args, **options)
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 65, in get_handler
    return get_internal_wsgi_application()
  File "/run/media/fv/hdd-1/PROJECTS/django-receipes/django_template/venv/lib/python3.9/site-packages/django/core/servers/basehttp.py", line 47, in get_internal_wsgi_application
    raise ImproperlyConfigured(
django.core.exceptions.ImproperlyConfigured: WSGI application 'django_project.wsgi.application' could not be loaded; Error importing module.