python - Django REST 框架；使用 'groups' 字段序列化用户模型时出现问题

Question

我正在尝试将 REST 框架添加到我现有的项目中。但是，每当我将 'groups' 添加到我的 UserSerializer 类中的 fields 时，我都会得到此回溯:

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8000/api/users/

Django Version: 1.10.7
Python Version: 3.6.3
Installed Applications:
['django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admin',
 'crispy_forms',
 'allauth',
 'allauth.account',
 'allauth.socialaccount',
 'blended_learning_portal.users.apps.UsersConfig',
 'blended_learning_portal.taskapp.celery.CeleryConfig',
 'blended_learning_portal.unit.apps.UnitConfig',
 'blended_learning_portal.data.apps.DataConfig',
 'debug_toolbar',
 'django_extensions',
 'graphos',
 'ckeditor',
 'ckeditor_uploader',
 'webpack_loader',
 'rest_framework']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'debug_toolbar.middleware.DebugToolbarMiddleware']



Traceback:

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/relations.py" in to_representation
  378.             url = self.get_url(value, self.view_name, request, format)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/relations.py" in get_url
  316.         return self.reverse(view_name, kwargs=kwargs, request=request, format=format)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/reverse.py" in reverse
  50.         url = _reverse(viewname, args, kwargs, request, format, **extra)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/reverse.py" in _reverse
  63.     url = django_reverse(viewname, args=args, kwargs=kwargs, **extra)

File "/home/michael/blportal/lib/python3.6/site-packages/django/urls/base.py" in reverse
  91.     return force_text(iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs)))

File "/home/michael/blportal/lib/python3.6/site-packages/django/urls/resolvers.py" in _reverse_with_prefix
  392.             (lookup_view_s, args, kwargs, len(patterns), patterns)

During handling of the above exception (Reverse for 'group-detail' with arguments '()' and keyword arguments '{'pk': 2}' not found. 0 pattern(s) tried: []), another exception occurred:

File "/home/michael/blportal/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  42.             response = get_response(request)

File "/home/michael/blportal/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/home/michael/blportal/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/michael/blportal/lib/python3.6/site-packages/django/views/decorators/csrf.py" in wrapped_view
  58.         return view_func(*args, **kwargs)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/viewsets.py" in view
  90.             return self.dispatch(request, *args, **kwargs)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
  489.             response = self.handle_exception(exc)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/views.py" in handle_exception
  449.             self.raise_uncaught_exception(exc)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
  486.             response = handler(request, *args, **kwargs)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/mixins.py" in list
  48.         return Response(serializer.data)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/serializers.py" in data
  738.         ret = super(ListSerializer, self).data

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/serializers.py" in data
  262.                 self._data = self.to_representation(self.instance)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/serializers.py" in to_representation
  656.             self.child.to_representation(item) for item in iterable

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/serializers.py" in <listcomp>
  656.             self.child.to_representation(item) for item in iterable

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/serializers.py" in to_representation
  500.                 ret[field.field_name] = field.to_representation(attribute)

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/relations.py" in to_representation
  520.             for value in iterable

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/relations.py" in <listcomp>
  520.             for value in iterable

File "/home/michael/blportal/lib/python3.6/site-packages/rest_framework/relations.py" in to_representation
  393.             raise ImproperlyConfigured(msg % self.view_name)

Exception Type: ImproperlyConfigured at /api/users/
Exception Value: Could not resolve URL for hyperlinked relationship using view name "group-detail". You may have failed to include the related model in your API, or incorrectly configured the `lookup_field` attribute on this field.

错误似乎来自 UserSerializer，而不是 GroupSerializer。它显然不知道在哪里寻找 group-detail(因为我在命名空间 api_v1 中有它。但是我不确定如何指定它。

api/views.py:

from django.contrib.auth.models import Group
from rest_framework import viewsets
from .serializers import UserSerializer, GroupSerializer

# We're using a modified User model
try:
    from django.contrib.auth import get_user_model
except ImportError:  # Django < 1.5
    from django.contrib.auth.models import User
else:
    User = get_user_model()


class UserViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows users to be viewed or edited.
    """
    queryset = User.objects.all()
    serializer_class = UserSerializer


class GroupViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows users to be viewed or edited.
    """
    queryset = Group.objects.all()
    serializer_class = GroupSerializer

api/serializers.py:

from django.contrib.auth.models import Group
from rest_framework import serializers


try:
    from django.contrib.auth import get_user_model
except ImportError:  # Django < 1.5
    from django.contrib.auth.models import User
else:
    User = get_user_model()


class UserSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        extra_kwargs = {'url': {'view_name': 'api_v1:user-detail'}}
        model = User
        fields = ('url', 'username', 'email', 'groups')


class GroupSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        extra_kwargs = {'url': {'view_name': 'api_v1:group-detail'}}
        model = Group
        lookup_field = 'id'
        fields = ('url', 'id', 'name')

api/urls.py:

from django.conf.urls import url, include
from rest_framework import routers
from . import views

router = routers.DefaultRouter()
router.register(r'users', views.UserViewSet)
router.register(r'groups', views.GroupViewSet)

urlpatterns = [
    url(r'^', include(router.urls)),
]

我希望这只是告诉 Django 在哪里寻找 group-detail 的问题。任何帮助将不胜感激，这让我发疯。

Answer 1

我想我忽略了您可以为每个字段添加一个 kwarg samespace。我有点傻。无论如何，在我的 serializers.py 中更改它是解决方案:

    extra_kwargs = {
        'url': {'view_name': 'api_v1:user-detail'},

        # Added this line:
        'groups': {'view_name': 'api_v1:group-detail'},
    }

顺便说一下，这是必要的，因为 rest_framework.routers.DefaultRouter 根本不处理命名空间。参见 this issue在 Git 上。