python - django 中的循环导入错误

Question

我将我的 django 结构组织成一个 views 和 urls 文件夹。在 /appfolder/urls/_ init _.py 或 url 中的任何地方导入 django.contrib.auth.views.login像这样查看文件夹:

from django.contrib.auth.views import login

我不断得到:

ImportError: cannot import name login

我认为这与更改后的结构有关。我想像这样将它包含在我的 url 模式中:

path('portal/', login, {'template_name': 'portal/index.html'})

如何在不出现循环导入错误的情况下导入登录信息？

目录结构

appfolder
│   
└─── __init__.py       
└─── admin.py
└─── apps.py   
└─── forms.py
└─── models.py         
│
└───urls
│   │   __init__.py     |
│   │   books_urls.py   |
|   |   movies_urls.py  |
|   |   portal_urls.py  |
│   |_ _ _ _ _ _ _ _ _ _|
|    
└───views
│   │   __init__.py      |
│   │   books_views.py   |
|   |   movies_views.py  |
|   |   portal_views.py  |
│   |_ _ _ _ _ _ _ _ _ _ |

appfolder/urls/_ init _.py

from django.urls import include
from django.contrib.staticfiles.urls import staticfiles_urlpatterns
from django.conf.urls.static import static
from django.conf import settings

from django.contrib.auth.views import login

from .books_urls import *
from .movies_urls import *
from .portal_urls import *

urlpatterns = [
    path('accounts/', include('django.contrib.auth.urls')),
    path('portal/', login, {'template_name': 'portal/index.html'}),
    path('portal/', include('appfolder.urls.portal_urls')),
    path('movies/', include('appfolder.urls.movies_urls')),
    path('books/', include('appfolder.urls.books_urls')),
]

urlpatterns += staticfiles_urlpatterns()
urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

堆栈跟踪:

> Unhandled exception in thread started by <function
> check_errors.<locals>.wrapper at 0x0000013AEBD7D048> Traceback (most
> recent call last):   File
> "C:\Users\User\Envs\webshop\lib\site-packages\django\utils\autoreload.py",
> line 225, in wrapper
>     fn(*args, **kwargs)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\core\management\commands\runserver.py",
> line 117, in inner_run
>     self.check(display_num_errors=True)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\core\management\base.py",
> line 379, in check
>     include_deployment_checks=include_deployment_checks,   File "C:\Users\User\Envs\webshop\lib\site-packages\django\core\management\base.py",
> line 366, in _run_checks
>     return checks.run_checks(**kwargs)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\core\checks\registry.py",
> line 71, in run_checks
>     new_errors = check(app_configs=app_configs)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\core\checks\urls.py",
> line 40, in check_url_namespaces_unique
>     all_namespaces = _load_all_namespaces(resolver)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\core\checks\urls.py",
> line 57, in _load_all_namespaces
>     url_patterns = getattr(resolver, 'url_patterns', [])   File "C:\Users\User\Envs\webshop\lib\site-packages\django\utils\functional.py",
> line 37, in __get__
>     res = instance.__dict__[self.name] = self.func(instance)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\urls\resolvers.py",
> line 533, in url_patterns
>     patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)   File
> "C:\Users\User\Envs\webshop\lib\site-packages\django\utils\functional.py",
> line 37, in __get__
>     res = instance.__dict__[self.name] = self.func(instance)   File "C:\Users\User\Envs\webshop\lib\site-packages\django\urls\resolvers.py",
> line 526, in urlconf_module
>     return import_module(self.urlconf_name)   File "C:\Users\User\Envs\webshop\lib\importlib\__init__.py", line 126, in
> import_module
>     return _bootstrap._gcd_import(name[level:], package, level)   File "<frozen importlib._bootstrap>", line 994, in _gcd_import   File
> "<frozen importlib._bootstrap>", line 971, in _find_and_load   File
> "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked 
> File "<frozen importlib._bootstrap>", line 665, in _load_unlocked  
> File "<frozen importlib._bootstrap_external>", line 678, in
> exec_module   File "<frozen importlib._bootstrap>", line 219, in
> _call_with_frames_removed   File "C:\Users\User\Desktop\project\company\com\com\urls.py", line 10, in
> <module>
>     path('', include('appfolder.urls')),   File "C:\Users\User\Envs\webshop\lib\site-packages\django\urls\conf.py",
> line 34, in include
>     urlconf_module = import_module(urlconf_module)   File "C:\Users\User\Envs\webshop\lib\importlib\__init__.py", line 126, in
> import_module
>     return _bootstrap._gcd_import(name[level:], package, level)   File "<frozen importlib._bootstrap>", line 994, in _gcd_import   File
> "<frozen importlib._bootstrap>", line 971, in _find_and_load   File
> "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked 
> File "<frozen importlib._bootstrap>", line 665, in _load_unlocked  
> File "<frozen importlib._bootstrap_external>", line 678, in
> exec_module   File "<frozen importlib._bootstrap>", line 219, in
> _call_with_frames_removed   File "C:\Users\User\Desktop\project\company\com\appfolder\urls\__init__.py",
> line 8, in <module>
>     from django.contrib.auth.views import login ImportError: cannot import name 'login'

Answer 1

你遇到的问题是，虽然

from .portal_urls import *

只是导入从当前文件目录中找到的 portal_urls.py 中的所有内容，这种类型的导入

import appfolder.urls.portal_urls

将在加载 appfolder/urls/portal_urls.py 之前同时加载 appfolder/__init__.py 和 appfolder/urls/__init__.py ( [*] 请参阅底部的示例)。

这就是为什么，在您的 appfolder/__init__.py 中，编译器通过了这个导入

...
from .portal_urls import *

在被这个噎住之前:

urlpatterns = [
    ...
    path('portal/', include('appfolder.urls.portal_urls')),

如果您以正常方式构建您的应用程序，则可以避免此问题，即

appfolder
│   __init__.py
│   urls.py
│
├───books
│       __init__.py
│       urls.py
│
├───movies
│       __init__.py
│       urls.py
│
└───portal
        __init__.py
        urls.py

所有 __init__.py 文件都是空的，appfolder/urls.py 包含

urlpatterns = [
    ...
    path(r'^portal/', include('appfolder.portal.urls')),
    path(r'^movies/', include('appfolder.movies.urls')),
    path(r'^books/', include('appfolder.books.urls')),

如果这些文件夹增长，这种结构还可以更轻松地将其中一个文件夹拉出到它自己的模块中。

[*] 如果您将 print(__file__) 放在每个 __init__.py 文件中，您可以检查导入的内容:

(dev) go|c:\srv\tmp> python -c "import appfolder.books.urls"
appfolder\__init__.py
appfolder\books\__init__.py