Django：如何通过过滤器查询集从 ForeignKey model 返回字段。 因为它不会抛出 JSON 可序列化

Question

我想从Contet model 返回一个字段，它是Saved model 的 ForeignKey 字段。 我正在使用filter查询集，因为它返回多个值。 但是，问题是我无法在Saved.objects.filter(user=self.request.user)之后使用content.slug从Content model 返回slug字段！

内容 model：

class Content(models.Model):
    title = models.CharField(max_length=200, blank=False)
    slug = models.CharField(max_length=200, blank=False)
    ...

我保存的 model：

class Saved(models.Model):
    content = models.ForeignKey('Content', on_delete=models.SET_NULL)
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    ...

我的观点：

class SavedList(viewsets.ModelViewset):
    serializer_class = SavedSerializer
    permission_classes = [permissions.IsAuthenticated]
    
    def get_queryset(self):
        return Saved.objects.filter(user=self.request.user)

    def list(self, request):
        savedList = []
        for i in self.get_queryset():
            dict = {
                'slug': i.content.slug,  # i want this
                'content': i.content,
                'user': i.user
            }
            savedList.append(dict)
        return Response(savedList)

当我运行它时，它返回Object of type 'Content' is not JSON Serializable ！

如何从Content model 中获取slug ？

Answer 1

该错误是因为您的def list()中的i是 class Content的 object 。

您可以通过创建嵌套序列化程序来实现它，如下所示。 可能您不需要def list()方法。

class UserSerializer(serializers.ModelSerializer):

    class Meta:
        model = settings.AUTH_USER_MODEL
        fields = '__all__' # provide the list fields from `settings.AUTH_USER_MODEL` to include in nested object.

class ContentSerializer(serializers.ModelSerializer):

    class Meta:
        model = Content
        fields = '__all__' # provide the list fields from `Content ` to include in nested object.

class SavedSerializer(serializers.ModelSerializer):
    
    content = ContentSerializer(many=True) # this will create a nested object.
    user = UserSerializer(many=True) # this will create a nested object.

    class Meta:
        model = Saved
        fields = ['content', 'user'] # you can add more fields of `Saved` model.