Django REST 框架："This field is required." required = False 和 unique_together

Question

我想用Django REST框架保存一个简单的模型。唯一的要求是在perform_create()方法中自动设置UserVote.created_by。此操作失败，出现以下异常：

{
    "created_by": [
        "This field is required."
    ]
}

我想是因为unique_together索引。

models.py:

class UserVote(models.Model):
    created_by = models.ForeignKey(User, related_name='uservotes')
    rating = models.ForeignKey(Rating)
    class Meta:
        unique_together = ('created_by', 'rating')

serializers.py

class UserVoteSerializer(serializers.ModelSerializer):
    id = serializers.IntegerField(read_only=True)
    created_by = UserSerializer(read_only=True)
    class Meta:
        model = UserVote
        fields = ('id', 'rating', 'created_by')

views.py

class UserVoteViewSet(viewsets.ModelViewSet):
    queryset = UserVote.objects.all()
    serializer_class = UserVoteSerializer
    permission_classes = (IsCreatedByOrReadOnly, )
    def perform_create(self, serializer):
        serializer.save(created_by=self.request.user)

如何在DRF中保存我的模型，而不需要用户提供created_by，而是在代码中自动设置此字段？

提前感谢！

Answer 1

我遇到了一个类似的问题，我通过显式创建一个新实例并将其传递给序列化程序来解决它。在UserVoteViewSet中，您必须将perform_create替换为create:

 def create(self, request, *args, **kwargs):
    uv = UserVote(created_by=self.request.user)
    serializer = self.serializer_class(uv, data=request.data)
    if serializer.is_valid():
        serializer.save()
        return Response(serializer.data, status=status.HTTP_201_CREATED)
    else:
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

Answer 2

我能够用views.py 中的一个liner解决这个问题

def create(self, request, *args, **kwargs):
    request.data.update({'created_by': request.user.id})
    return super(UserVoteViewSet, self).create(request, *args, **kwargs)

由于此视图期望用户通过身份验证，所以不要忘记为rest_framework.permissions.IsAuthenticated 扩展permission_classes

Answer 3

另一种奇怪的方法是使用类似的信号

@receiver(pre_save, sender=UserVote)
def intercept_UserVote(sender, instance, *args, **kwargs):
    import inspect
    for frame_record in inspect.stack():
        if frame_record[3]=='get_response':
            request = frame_record[0].f_locals['request']
            break
    else:
        request = None
    instance.pre_save(request)

然后基本上你可以在你的模型中定义pre_save

def pre_save(self, request):
    # do some other stuff
    # Although it shouldn't happen but handle the case if request is None
    self.created_by = request.user

这个系统的优点是您可以为每个模型使用相同的代码。如果您需要更改任何内容，只需更改pre_save()即可。你也可以添加更多的东西

Answer 4

将以下内容添加到ViewSet:

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

Serializer上的以下内容：

class Meta:
    extra_kwargs = {
        'user': {
            'required': False,
        },
    } 

Answer 5

以下代码对我有效。

在许多实验发现一些东西后，甚至我也面临着同样的错误，所以在类meta中添加了serializer.py中的所有字段，如下所示-

class Emp_UniSerializer( serializers.ModelSerializer ):
    class Meta:
        model = table
        fields = '__all__'  # To fetch For All Fields
        extra_kwargs = {'std_code': {'required': False},'uni_code': {'required': False},'last_name': {'required': False},'first_name': {'required': False}}

在这里，我们可以更新"extra_kwargs"中的任何字段，它不会显示错误["This field is required."]