在Django Rest Framework中发布外键关系 [英] Posting a foreign key relationship in Django Rest Framework

问题描述

在我的模型中，我有以下课程:

In my models, I have the following classes:

class Topic(models.Model):
    name = models.CharField(max_length=25, unique=True)

class Content(models.Model):
    title = models.CharField(max_length=255)
    body = models.TextField()
    topic = models.ForeignKey(Topic, blank=True, null=True)

我的序列化器是这样的:

class TopicSerializer(serializers.ModelSerializer):
     class Meta:
         model = Topic
         fields = ('name')

class ContentSerializer(serializers.ModelSerializer):
     topic = TopicSerializer(read_only=True)
     class Meta:
          model = Content
          fields = ('title', 'body', 'topic')

好的，因此在我的 urls 文件中，我具有以下模式:

Alright, so in my urls file, I have the following pattern:

urlpatterns = [
    ...
    url(r'^api/topic_detail/(?P<name>[a-zA-Z0-9-]+)/content_list/$', views.topic_content_list, name='topic_content_list'),
    ...
]

因此，当用户说/api/topic_detail/sports/content_list/时，我们将获得所有主题为 sports 的内容的列表.现在我想要的是，如果我们将以下数据 POST 发布到上述URL，那么将创建一个Content对象，其中的主题字段会自动与体育相关.

Therefore, when the user goes to say /api/topic_detail/sports/content_list/, we get a list of all the contents that has the topic of sports. Now what I want is if we POST the following data to the above URL, then a Content object is created with the topic field related automatically to sports.

我正尝试在我的视图中以以下方式执行此操作:

I am trying to do this the following way in my views:

@api_view(['GET', 'POST'])
def topic_content_list(request, name):
    try:
        topic = Topic.objects.get(name=name)
    except:
        return Response(status=status.HTTP_404_NOT_FOUND)

    if request.method == 'GET':
        contents = Content.objects.filter(topic=topic)
        serializer = ContentSerializer(contents, many=True)
        return Response(serializer.data)

    elif request.method == 'POST':
        request.data["topic"] = topic
        serializer = ContentSerializer(data=request.data)
        print request.data
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

现在可以说我进入URL /api/topic_detail/sports/content_list/并将其发布:

Now lets say I go the URL /api/topic_detail/sports/content_list/ and POST this:

{
    "title": "My blog post",
    "body" : ".....",
}

将创建内容对象，并且正确设置了标题和正文字段.但是，主题字段设置为null.我怎样才能解决这个问题?感谢您的帮助.

The content object gets created and the title and body field is set properly. However, the topic field is set to null. How can I fix this? Any help is appreciated.

另外，请不要建议使用通用视图集，因为我对这么多自动发生的事情感到不舒服.

Also, please don't suggest using generic viewsets, as I am uncomfortable with so many things happening automatically.

编辑

好的，所以我纠正了我的愚蠢错误:

Alright, so I fixed my dumb mistake :

class ContentSerializer(serializers.ModelSerializer):
     topic = TopicSerializer(read_only=False)
     class Meta:
          model = Content
          fields = ('title', 'body', 'topic')

也就是说，我将read_only参数设置为False.但是，现在该帖子创建了一个新错误:

That is, I set the read_only argument to False. However, now the post creates a new error:

{
    "topic": {
        "non_field_errors": [
            "Invalid data. Expected a dictionary, but got Topic."
        ]
    }
}

我敢肯定，这是指我要发送的data.website不是JSON，而是一个Django模型实例.如何对单个实例进行JSON化?

This I am pretty sure refers to the fact that the data.website I'm sending in is not JSON, but instead just a Django model instance. How can I JSONify the single instance?

推荐答案

这是来自您的序列化器.

This is from your serializer.

     topic = TopicSerializer(read_only=True)

这意味着您的主题是只读的，因此当您尝试保存序列化程序时，不会保存主题.删除它，问题将得到解决.

It means your topic is read only so when you are trying to save your serializer, topic is not getting saved. Remove that and problem would be fixed.

现在，根据第二个错误，这是因为它期待一个dict，并且您正在传递模型实例，所以有两个选择.要么手动创建字典.

Now as per the second error, it is because it is expecting a dict and you are passing the model instance, so you have two options. Either create the dict by hand.

topic_dict = {"name":topic.name}

并在request.data中将其作为主题"传递，然后保存或提供topic_id，因为存在外键关系，它应该可以工作.

and pass that as 'topic' in request.data and then save or give the topic_id, as there is a foreign key relationship, it should work.

所以会是这样:

request.data["topic_id"] = topic.id

现在，您选择要做的完全由您决定.

Now what you choose to do is totally upto you.

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