Django新手教程中出现ModuleNotFoundError: No module named 'polls'报错求助

环境与问题背景 #

• Django版本：4.2
• Python版本：3.10
• 开发工具：VS Code
• 操作：跟随Django官方教程创建polls投票应用，编写代码后运行出现ModuleNotFoundError: No module named 'polls'错误。

编写的代码文件 #

polls/views.py

from django.http import HttpResponse
def index(request):
    return HttpResponse("Hello, world. You're at the polls index.")

polls/urls.py

from django.urls import path
import views
urlpatterns = [
    path('', views.index, name='index'),
]

mysite/urls.py

from django.contrib import admin
from django.urls import include, path
urlpatterns = [
    path('polls/', include('polls.urls')),
    path('admin/', admin.site.urls),
]

报错信息 #

Traceback (most recent call last):
  File "a:\experimental_files\vs_code\djangoExer\mysite\mysite\tempCodeRunnerFile.py", line 5, in <module>
    path('polls/', include('polls.urls')),
  File "c:\users\yasir amin brohi\desktop\django\django\urls\conf.py", line 38, in include
    urlconf_module = import_module(urlconf_module)
  File "C:\Users\Yasir Amin Brohi\AppData\Local\Programs\Python\Python310\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 992, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'polls'

原因分析 #

1. polls应用未被注册到Django项目的已安装应用列表中，导致Django无法识别该模块。
2. polls/urls.py中的import views不符合Python 3的相对导入规范，可能引发导入路径问题。
3. 若polls目录缺少__init__.py文件，会导致Python无法将其识别为合法模块。

解决方案 #

1. 注册polls应用到INSTALLED_APPS #

打开mysite/settings.py，找到INSTALLED_APPS列表，添加'polls'：

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # 添加此行注册polls应用
    'polls',
]

2. 修正polls/urls.py的导入语句 #

将import views改为Python 3支持的相对导入：

from django.urls import path
# 使用相对导入当前应用的views模块
from . import views

urlpatterns = [
    path('', views.index, name='index'),
]

3. 确认目录结构合法性 #

确保项目目录结构如下（重点是polls目录下存在__init__.py）：

mysite/
    manage.py
    mysite/
        __init__.py
        settings.py
        urls.py
        ...
    polls/
        __init__.py  # 必须存在，标识为Python模块
        admin.py
        apps.py
        models.py
        urls.py
        views.py
        ...

4. 验证修复结果 #

在项目根目录（包含manage.py的文件夹）执行以下命令启动开发服务器：

python manage.py runserver

访问http://localhost:8000/polls/，若页面显示"Hello, world. You're at the polls index."，则问题已解决。

内容的提问来源于stack exchange，提问作者user18939954