进行权限和身份验证时出现DRF错误

Question

这是我的 models.py

from __future__ import unicode_literals
from django.db import models

class Snippet(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    title = models.CharField(max_length=100, blank=True, default='')
    code = models.TextField()
    linenos = models.BooleanField(default=False)
    owner = models.ForeignKey('auth.User', related_name='snippets', on_delete=models.CASCADE)
    highlighted = models.TextField()

    class Meta:
        ordering = ('created',)

这是我的 serializers.py

from .models import Snippet
from django.contrib.auth.models import User


class SnippetSerializer(serializers.ModelSerializer):
    owner = serializers.ReadOnlyField(source='owner.username')
    class Meta:
        model = Snippet
        fields = ('id', 'title', 'code', 'linenos')


class UserSerializer(serializers.ModelSerializer):
    snippets = serializers.PrimaryKeyRelatedField(many=True, queryset=Snippet.objects.all())

    class Meta:
        model = User
        fields = ('id', 'username', 'snippets')

这是我的 permissions.py

from rest_framework import permissions
class IsOwnerOrReadOnly(permissions.BasePermission):
    def has_object_permission(self, request, view, obj):
        if request.method in permissions.SAFE_METHODS:
            return True
        return obj.owner == request.user

这是我的 views.py

from .models import Snippet
from .serializers import SnippetSerializer, UserSerializer
from rest_framework import generics
from django.contrib.auth.models import User
from rest_framework import permissions
from .permissions import IsOwnerOrReadOnly

class SnippetList(generics.ListCreateAPIView):
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,)

    def perform_create(self, serializer):
        serializer.save(owner=self.request.user)

class SnippetDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,
                                            IsOwnerOrReadOnly,)

class UserList(generics.ListAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer

class UserDetail(generics.RetrieveAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer

这是我的 urls.py

from django.conf.urls import url, include
from v2 import views

urlpatterns = [
    # url(r'^snippets/$', views.snippet_list),
    # url(r'^snippets/(?P<pk>[0-9]+)/$', views.snippet_detail),
    url(r'^snippets/$', views.SnippetList.as_view()),
    url(r'^snippets/(?P<pk>[0-9]+)/$', views.SnippetDetail.as_view()),
    url(r'^users/$', views.UserList.as_view()),
    url(r'^users/(?P<pk>[0-9]+)/$', views.UserDetail.as_view()),
    url(r'^api-auth/', include('rest_framework.urls')),
]

我正在通过检查Django rest框架文档来做，但是， 它向我显示错误为

OperationalError at /snippets/
(1054, "Unknown column 'v2_snippet.owner_id' in 'field list'")

请看看这个。