ObjectDoesNotExist不捕获DidNotExist异常

Question

我试图捕获一个DidNotExist异常，并且很难检查抛出该异常的代码。我无法到达将其抛出到pdb中的那一行，并且在调试跟踪中，没有关于引发异常的对象的信息，因为它包含在实例变量下，因此django跟踪不会显示其值。

我已经阅读了https://docs.djangoproject.com/zh-CN/1.11/ref/exceptions/#objectdoesnotexist上的文档，并在“ 捕获任何DidNotExist错误”中发现了这个问题。这两个都表明，要捕获任何DidNotExist异常，只需导入ObjectDoesNotExist即可覆盖所有异常。在我来说不是。我的除ObjectDoesNotExist块外未捕获到异常。

码：

from django.core.exceptions import ObjectDoesNotExist

def check_permission(user):
    """function checks whether the user is in the list of allowed groups"""
    for option in ALLOWED: # list of groups, constant
        try:
            if user.groups.get().name == option:
                return True
        except ObjectDoesNotExist:
            pass
        else:
            pass
    return False

跟踪显示为：

File 
".../lib/python3.6/site-packages/django/db/models/query.py", line 379, in get self.model._meta.object_name

django.contrib.auth.models.DoesNotExist: Group matching query does not exist.

这是从我的代码行中抛出的：

if user.groups.get().name == option

尝试访问django.contrib.auth.models.DoesNotExist只会返回一个

AttributeError: model 'django.contrib.auth.models' has no attribute 'DoesNotExist'

我该如何捕捉？有时用户将没有任何组，即使该站点是为永不中断而设计的，但仍令我感到不安的是，这里存在易破解的代码。

编辑：python 3.6.2 Django 1.11

完整跟踪：

Traceback (most recent call last):
  File ".../lib/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner
response = get_response(request)
  File ".../lib/python3.6/site-packages/django/core/handlers/base.py", line 249, in _legacy_get_response
response = self._get_response(request)
  File ".../lib/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response
response = self.process_exception_by_middleware(e, request)
  File ".../lib/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File ".../lib/python3.6/site-packages/django/contrib/auth/decorators.py", line 23, in _wrapped_view
return view_func(request, *args, **kwargs)
  File ".../lib/python3.6/site-packages/django/views/generic/base.py", line 68, in view
return self.dispatch(request, *args, **kwargs)
  File ".../lib/python3.6/site-packages/django/views/generic/base.py", line 88, in dispatch
return handler(request, *args, **kwargs)
  File "/Users/Mark/Desktop/Professional/FSC/water/WATER/sharedClasses.py", line 116, in get
return self.permission_denied_page(request, plans)
  File "/Users/Mark/Desktop/Professional/FSC/water/WATER/sharedClasses.py", line 68, in permission_denied_page
their_acccount = user.groups.get().name
  File ".../lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
  File ".../lib/python3.6/site-packages/django/db/models/query.py", line 379, in get
self.model._meta.object_name
django.contrib.auth.models.DoesNotExist: Group matching query does not exist.

Answer 1

您应该导入Group并像这样捕获：

from django.contrib.auth.models import Group

try:
    // your code
except Group.DoesNotExist:
   // to handle

顺便说一句，为什么不以非常优化的方式编写如下的方法：

def check_permission(user):
   """return true if the user is in options, false if not"""
   if user.groups.filter(name__in=ALLOWED).exists():
      return True
   else:
      return False