TypeError while using django rest framework tutorial

Question

I am new to using Django Rest framework, i am following this tutorial Django-Rest-Framework

Instead of snippets my model consists of a userprofile as given below:

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)

The first part of the tutorial ran fine, got the desired output in json format as mentioned, however the second tutorial onwards i am getting type error:

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

The rest of the code is almost same as given in the above link in 2nd part and 3rd part: 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/$', views.UserProfileList.as_view()),
    url(r'^userprofile/(?P<pk>[0-9]+)/$', views.UserProfileDetail.as_view()),
)

urlpatterns = format_suffix_patterns(urlpatterns)

I am missing something very obvious, tried a lot to search what exactly the "type object not iterable" means in this context, and which object is causing the problem, but no luck. I am using Django Rest Framework version 2.3.

Thanks in advance

Solution 1

As pointed out by Daniel above, i had this stupid snippet in the settings file, which was causing the problem,

#REST_FRAMEWORK = {
#   '''Use hyperlinked styles by default'''
#   '''only used if serializer_class attribute is not set on a view'''
#   'DEFAULT_MODEL_SERIALIZER_CLASS':
#         'rest_framkework.serializers.HyperLinkedModelSerializer',
#   'DEFAULT_PERMISSION_CLASSES':
#          'rest_framework.permissions.DjangoModelPermissionsOrAnonReadOnly'
# }

Commmented this and it worked.

Solution 2

Just to let others know, I kept getting this same error and found that I forgot to include a comma in my REST_FRAMEWORK. I had this:

'DEFAULT_PERMISSION_CLASSES': (
    'rest_framework.permissions.IsAuthenticated'
),

instead of this:

'DEFAULT_PERMISSION_CLASSES': (
    'rest_framework.permissions.IsAuthenticated',
),

The comma defines this as a one-element tuple

Solution 3

In my case the typo was in views.py. Instead of ...

permission_classes = (permissions.IsAuthenticated,)

... I had ...

permission_classes = (permissions.IsAuthenticated)

Solution 4

I had the same error when I used custom permissions, because of a 'typo'

I had:

@permission_classes(EventByFacilityPermissions)
class EventByFacilityViewSet(viewsets.ModelViewSet):

instead of:

@permission_classes((EventByFacilityPermissions,))
class EventByFacilityViewSet(viewsets.ModelViewSet):

Solution 5

Pass the authentication class inside your class instead of in your settings.py if you need authentication just in some classes, and do like this:

authentication_classes = [TokenAuthentication, ]

instead of like this:

authentication_classes = TokenAuthentication

View more solutions

Comments

[Daniel Roseman]

It seems that permission_classes is being set to None on your UserProfileList class. But that shouldn't happen with the code you show here, because it is set to api_settings.DEFAULT_PERMISSION_CLASSES in views.APIView, which generics.GenericAPIView inherits from. Have you overridden the settings anywhere?

[Sirius]

@DanielRoseman: Yup that was the problem, thanks a lot mate :), actually i followed quick tutorial in which there was this 'DEFAULT_PERMISSION_CLASSES': # 'rest_framework.permissions.DjangoModelPermissionsOrAnonRead‌​Only'. Commented this and it worked.

[Keshav Agrawal]

You saved me lot of frustration!

[Max Heiber]

I think Python needs the trailing comma in order to recognize the expression as a 1-element tuple instead of just a regular expression in parentheses: wiki.python.org/moin/TupleSyntax

[Rutwick Gangurde]

Great! I removed that comma initially because I thought its a typo. Thanks for the tip!

[Andrés Muñoz]

reading this is the more luckiest thing I have in a long time

[MarkK]

Thank you for this helped my a lot!

[Harper]

I know commenting should not be used for thanking but... In this case a simple upvote is just not enough. ty!

[Neil]

Oh my. Principle of least surprise anyone?

[davyria]

In my case, instead DEFAULT_PERMISION_CLASSES, the missing comma was in DEFAULT_AUTHENTICATION_CLASSES (with 1 element only). Thank you!