Django REST 框架：“BasePermissionMetaclass”对象不可迭代

Question

Python/Django n00b 从 javascript 迁移过来。

尝试使用 Django REST 框架添加 API 端点，我希望最终能够使用 PATCH 请求的主体更新用户，但现在我只希望它不会引发 500 错误。

我已将此添加到 urlpatterns：

url(r'update/$', views.UpdateView.as_view(), name="update_user"),

这应该带来这种观点：

from django.contrib.auth.models import User
from rest_framework.generics import UpdateAPIView
from .serializers import UserSerializer

class UpdateView(UpdateAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer

UserSerializer 如下所示：

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('username', 'pk', 'status')

似乎每次我访问该路线时都会得到这个：

TypeError at /api/update/
'BasePermissionMetaclass' object is not iterable

我不知道自己在做什么 - 以前有人见过吗？

更新：完整追溯：

Internal Server Error: /api/update/
Traceback (most recent call last):
  File "path/to/myapp/env/lib/python2.7/site-packages/django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "path/to/myapp/env/lib/python2.7/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "path/to/myapp/env/lib/python2.7/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "path/to/myapp/env/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "path/to/myapp/env/lib/python2.7/site-packages/django/views/generic/base.py", line 68, in view
    return self.dispatch(request, *args, **kwargs)
  File "path/to/myapp/env/lib/python2.7/site-packages/rest_framework/views.py", line 495, in dispatch
    response = self.handle_exception(exc)
  File "path/to/myapp/env/lib/python2.7/site-packages/rest_framework/views.py", line 455, in handle_exception
    self.raise_uncaught_exception(exc)
  File "path/to/myapp/env/lib/python2.7/site-packages/rest_framework/views.py", line 483, in dispatch
    self.initial(request, *args, **kwargs)
  File "path/to/myapp/env/lib/python2.7/site-packages/rest_framework/views.py", line 401, in initial
    self.check_permissions(request)
  File "path/to/myapp/env/lib/python2.7/site-packages/rest_framework/views.py", line 333, in check_permissions
    for permission in self.get_permissions():
  File "path/to/myapp/env/lib/python2.7/site-packages/rest_framework/views.py", line 280, in get_permissions
    return [permission() for permission in self.permission_classes]
TypeError: 'BasePermissionMetaclass' object is not iterable

Answer 1

您在DEFAULT_PERMISSION_CLASSES 值中输入了错误的逗号，因此 Django 将其视为字符串，而不是元组。

解决方案：

REST_FRAMEWORK = {
   ...
   'DEFAULT_PERMISSION_CLASSES': ( 'rest_framework.permissions.IsAdminUser', ),
   ...
}

Answer 2

我遇到了同样的问题，但是找错了地方。我制作了具有权限的mixin类并且有代码

permission_classes = (
    permissions.IsAuthenticated
)

但应该是

permission_classes = (
    permissions.IsAuthenticated,
#                              ^
#                         a comma here
)

所以不要忘记寻找其他具有权限的类。我希望它会对某人有所帮助。

Answer 3

作为可能在这里搜索的其他人的参考，这也可能是一个问题..

from django.contrib.auth.models import User
from rest_framework.generics import UpdateAPIView
from .serializers import UserSerializer

class UpdateView(UpdateAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer
    permission_classes = IsAuthenticated

应该改为：

    from django.contrib.auth.models import User
    from rest_framework.generics import UpdateAPIView
    from .serializers import UserSerializer

    class UpdateView(UpdateAPIView):
        queryset = User.objects.all()
        serializer_class = UserSerializer
        permission_classes = [IsAuthenticated]

Answer 4

Junst 万一this 也可以解决。至少解决了我的问题

Answer 5

只是为了完成@ihafurr 的回答。

permission_classes 应该是可迭代的，因为该变量是由 :func:viewsets.ModelViewSet.get_permission 调用的 (https://www.cdrf.co/3.12/rest_framework.viewsets/ModelViewSet.html):

def get_permissions(self):
    return [permission() for permission in self.permission_classes]

将此类方法的最后一行更改为以下内容可以克服可迭代性要求。

return [permission() for permission in self.permission_classes] if isinstance(self.permission_classes], Iterable) else [self.permission_classes]

Iterable 来自哪里

try:
    from collections.abc import Iterable  # for Python >= 3.6
except ImportError:
    from collections import Iterable

Answer 6

@permission_classes((AllowAny,))

您必须确保 逗号