Django REST框架：serializers_user_data.owner_id处的IntegrityError不能为NULL

Question

I am following django REST framework tutorial of Authentication & Permissions. As per tutorial i defined models and views buy i am getting the error below:

IntegrityError at serializers_user_data.owner_id may not be NULL

Here is my code:

models.py

class User_Data(models.Model):
    owner = models.ForeignKey('auth.User', related_name='user_datas')    
    user_name = models.CharField(max_length = 100, blank = True)
    user_email = models.CharField(max_length = 100, blank = True)
    user_city = models.CharField(max_length = 50, blank = True)

    class Meta:
        ordering = ['user_name']

    def __unicode__(self):
        return self.user_name

view.py

class User_Mixing():
    queryset = User_Data.objects.all()
    serializer_class = User_Data_Serializers
    permission_classes = (IsOwnerOrReadOnly,)

    def pre_save(self, obj):
        obj.owner = self.request.user
        print obj.owner

class User_list(User_Mixing, generics.ListCreateAPIView):
    pass

class User_detail(User_Mixing, generics.RetrieveUpdateDestroyAPIView):
    pass

Also help me with related_names in foreign key. For what purpose it is used??

Answer 1

I used perform_create method instead of pre_save

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

Answer 2

Set ipdb in your code

    def pre_save(self, obj):
    import ipdb; ipdb.set_trace()
    obj.owner = self.request.user
    print obj.owner

And check the request.user attribute to understand the error.