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问如何使用外键发布和获取模型
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Stack Overflow用户

提问于 2022-06-01 23:27:49

回答 1查看 205关注 0票数 0

我正在从事一个NextJS + Django REST框架项目，其中有三个模型: Document、MySource和QuestionBlock。

文档与几个链接到所创建文档的“question_blocks”一起创建。它们是一起创建的，我已经用嵌套序列化器实现了这一点。
创建文档后，我希望能够发布链接到文档的MySource模型。然后，当我对文档发出GET请求时，还应该显示所有mysource对象。

POST请求:注意我如何将文档的id放在我想要链接的.中

{
  "url": "urlasdf",
  "title": "tuitle",
  "publisher": "afdfas ",
  "desc": "qwefqwef",
  "summary": "asdfasdf",
  "document": "J9DY2pE"
}

GET请求:我希望文档GET请求显示如下所示。

"id": "LwpQr6Y",
    "question_blocks": [
        {
            "id": 16,
            "document": "LwpQr6Y",
            "title": "question 4",
            "content": "qweqgadssdffasdf asdf"
        },
        ]
    "mysource": [
                {
            "id": 16,
            "url": "google.com",
            etc. . .
        },
        ],
    "title": "renamed title",
    "template": "commonapp",
    "updated": "2022-05-19T02:16:00+0000",
    "created": "2022-04-21T06:59:05+0000"

奇怪的是，我没有看到下面的代码有任何错误，而且功能本身也正常工作。但是，当我试图获得至少有一个mysource对象的文档时，加载它需要几分钟时间，这让我认为我的代码有问题，可能会让DRF自己重复。

models.py

class Document(models.Model):
    id = HashidAutoField(primary_key=True)
    title = models.CharField(max_length=100, default="Untitled")
    template = models.CharField(max_length=100, default="")
    updated = models.DateTimeField(auto_now=True)
    created = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.title

class QuestionBlock(models.Model):
    id = models.AutoField(primary_key=True)
    document = models.ForeignKey(
        Document,
        related_name="question_blocks",
        on_delete=models.CASCADE,
        null=True,
        blank=True,
    )
    title = models.CharField(max_length=500, default="")
    content = models.CharField(max_length=100000, default="", blank=True)

class MySource(models.Model):
    id = models.AutoField(primary_key=True)
    document = models.ForeignKey(
        Document,
        related_name="mysource",
        on_delete=models.CASCADE,
        null=True,
        blank=True,
    )
    url = models.CharField(max_length=500, default="")
    title = models.CharField(max_length=500, default="", blank=True)
    publisher = models.CharField(max_length=500, default="", blank=True)
    desc = models.CharField(max_length=500, default="", blank=True)
    summary = models.CharField(max_length=500, default="", blank=True)

serializers.py

class MySourceSerializer(serializers.ModelSerializer):
    class Meta:
        model = MySource
        fields = ("id", "url", "title", "publisher", "desc", "summary")

    def to_representation(self, instance):
        self.fields["document"] = DocumentSerializer(read_only=True)
        return super(MySourceSerializer, self).to_representation(instance)


class DocumentSerializer(serializers.ModelSerializer):
    id = HashidSerializerCharField(source_field="documents.Document.id", read_only=True)
    question_blocks = QuestionBlockSerializer(many=True)
    mysource = MySourceSerializer(many=True)

    class Meta:
        model = Document
        fields = "__all__"

    def create(self, validated_data):
        question_blocks = validated_data.pop("question_blocks")
        document = Document.objects.create(**validated_data)
        for qBlock in question_blocks:
            QuestionBlock.objects.create(document=document, **qBlock)
        document.save()
        return document

编辑：添加QuestionBlockSerializer以获取更多上下文

class QuestionBlockSerializer(serializers.ModelSerializer):
    document = serializers.PrimaryKeyRelatedField(
        pk_field=HashidSerializerCharField(source_field="documents.Document.id"),
        read_only=True,
    )

    class Meta:
        model = QuestionBlock
        fields = "__all__"
        optional_fields = ["content"]

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回答 1

Stack Overflow用户

发布于 2022-06-01 23:51:51

我认为做这件事的合适方法可能是这样的：

###imports
from django.forms.models import model_to_dict


class DocumentListingField(serializers.RelatedField):
    def to_representation(self, instance):
        return model_to_dict(instance.document)

然后在MySourceSerializer中删除to_representation函数并更新如下内容：

class MySourceSerializer(serializers.ModelSerializer):
    document = DocumentListingField(many=False, read_only=True)

    class Meta:
        model = MySource
        fields = (
            "id", "url", "title", "publisher", "desc", "summary", "document")

*编辑:我将read_only集添加到True，因为这些模型使用的哈希菲尔德并不容易选择。

**编辑:导致响应缓慢的原因是，您有一个循环调用序列化程序，因此系统永远不知道何时停止。就在这里：

class MySourceSerializer(serializers.ModelSerializer):
    def to_representation(self, instance):
        ...
        self.fields["document"] = DocumentSerializer(read_only=True) 
        #Mysource its calling Documentserializer
            ...
    #And here:
class DocumentSerializer(serializers.ModelSerializer):
    ...
    mysource = MySourceSerializer(many=True) #this one its calling the MysorceSerialize, so there are a endless loop recursion