使用django rest框架教程时出现TypeError

我是使用Django Rest框架的新手,我正在遵循这个教程 Django-Rest-Framework

我的模型不是代码片段,而是由下面给出的userprofile组成:

class UserProfile(models.Model):
      user = models.OneToOneField(User)
      emp_code = models.CharField(max_length=10, blank=True)
      user_type = models.IntegerField(max_length=1, default=0, choices=USER_TYPE)
      group = models.ForeignKey(Group, null=True, blank=True)
      status = models.SmallIntegerField(max_length=1,default=0)
      added_on = models.DateTimeField(auto_now_add=True)

本教程的第一部分运行正常,如上所述以json格式获得所需的输出,但是第二个教程以后我得到了类型错误:

TypeError at /authentication/userprofile/
'type' object is not iterable
Request Method: GET
Request URL:    http://*****.com/authentication/userprofile/
Django Version: 1.6
Exception Type: TypeError
Exception Value:    
'type' object is not iterable
Exception Location: /home/web/cptm_venv/lib/python2.7/site-     packages/rest_framework/views.py in get_permissions, line 226
Python Executable:  /usr/bin/python
Python Version: 2.7.3
Python Path:    
['/home/web/cptm_venv/lib/python2.7/site-packages',
 '/home/web/cptm',
 '/home/web/cptm_venv/lib/python2.7/site-packages',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-linux2',
 '/usr/lib/python2.7/lib-tk',
 '/usr/lib/python2.7/lib-old',
 '/usr/lib/python2.7/lib-dynload',
 '/usr/local/lib/python2.7/dist-packages',
 '/usr/lib/python2.7/dist-packages',
 '/usr/lib/pymodules/python2.7']
 Server time:   Wed, 11 Dec 2013 17:33:54 +0530
 Traceback Switch to copy-and-paste view

/home/web/cptm_venv/lib/python2.7/site-packages/django/core/handlers/base.py in get_response
                response = wrapped_callback(request, *callback_args, **callback_kwargs) ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/django/views/generic/base.py in view
        return self.dispatch(request, *args, **kwargs) ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/django/views/decorators/csrf.py in    wrapped_view
    return view_func(*args, **kwargs) ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/rest_framework/views.py in dispatch
        response = self.handle_exception(exc) ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/rest_framework/views.py in dispatch
        self.initial(request, *args, **kwargs) ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/rest_framework/views.py in initial
    self.check_permissions(request) ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/rest_framework/views.py in   check_permissions
     for permission in self.get_permissions(): ...
? Local vars
/home/web/cptm_venv/lib/python2.7/site-packages/rest_framework/views.py in get_permissions
    return [permission() for permission in self.permission_classes] ...
? Local vars

其余代码几乎与第二部分和第三部分中的上述链接中给出的相同:views.py

from apps.authentication.models import UserProfile
from apps.authentication.serializers import UserProfileSerializer
from rest_framework import mixins
from rest_framework import generics

class UserProfileList(mixins.ListModelMixin,
              mixins.CreateModelMixin,
              generics.GenericAPIView):
    queryset = UserProfile.objects.all()
    serializer_class = UserProfileSerializer

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)


class UserProfileDetail(mixins.RetrieveModelMixin,
                mixins.UpdateModelMixin,
                mixins.DestroyModelMixin,
                generics.GenericAPIView):
    queryset = UserProfile.objects.all()
    serializer_class = UserProfileSerializer

    def get(self, request, *args, **kwargs):
        return self.retrieve(request, *args, **kwargs)

    def put(self, request, *args, **kwargs):
        return self.update(request, *args, **kwargs)

    def delete(self, request, *args, **kwargs):
        return self.destroy(request, *args, **kwargs)

urls.py

from django.conf.urls import patterns, url
from rest_framework.urlpatterns import format_suffix_patterns
from apps.authentication import views

urlpatterns = patterns('',
    url(r'^userprofile/$', views.UserProfileList.as_view()),
    url(r'^userprofile/(?P[0-9]+)/$', views.UserProfileDetail.as_view()),
)

urlpatterns = format_suffix_patterns(urlpatterns)

我遗漏了一些非常明显的东西,尝试了很多东西来搜索"类型对象不可迭代"在这个上下文中意味着什么,以及哪个对象导致问题,但没有运气.我正在使用Django Rest Framework 2.3版.

提前致谢