使用邮递员发布请求 Manytomany 字段 DRF

Question

目标：从 Postman 使用“POST”在数据库中创建一个新条目。

我正在尝试从 Postman 发送数据，并且我正在使用嵌套序列化。我已经更改了我在下面分享了 sn-p 的创建方法。另外，我试过这个solution，但没有用。有人可以指出我犯的错误吗？

当我尝试作为表单数据发布时，错误是{"magazine":["This field is required."]}。 当我尝试将其作为原始数据发布时，错误为Direct assignment to the forward side of a many-to-many set is prohibited. Use magazine.set() instead.

这是我的模型：

class Article(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField()
    author = models.ForeignKey('authors.Author', on_delete=models.CASCADE)
    magazine = models.ManyToManyField('articles.Magazine')

    def __str__(self):
        return self.title


class Magazine(models.Model):
    name = models.CharField(max_length=30)
    title = models.CharField(max_length=100)

    def __str__(self):
        return self.name

这是我的序列化器：

class MagazineSerializer(serializers.ModelSerializer):
    class Meta:
        model = Magazine
        fields = '__all__'

class ArticleSerializer(serializers.ModelSerializer):
    author = AuthorSerializer(read_only=True, many=False)
    magazine = MagazineSerializer(many=True)
    class Meta:
        model = Article
        fields = [
            'title',
            'content',
            'author',
            'magazine',
        ]

    def create(self, validated_data):
        allmags = []
        magazine = validated_data.pop('magazine')
        for i in magazine:
            if Magazine.objects.get(id=magazine["id"]).exists():
                mags = Magazine.objects.get(id=magazine["id"])
                allmags.append(mags)
            else:
                return Response({"Error":  "No such magazine exists"}, status=status.HTTP_400_BAD_REQUEST)
            
        validated_data['author'] = self.context['request'].user
        validated_data['magazine'] = allmags
        return Article.objects.create(**validated_data)

这是我的看法：

class ArticleViewSet(viewsets.ModelViewSet):
    queryset = Article.objects.all()
    serializer_class = ArticleSerializer

class MagazineViewSet(viewsets.ModelViewSet):
    queryset = Magazine.objects.all()
    serializer_class = MagazineSerializer

    serializer_action_class = {
        'get_articles': MagazineSerializer,
    }

    @action(detail=True, url_path='articles', url_name='articles')
    def get_articles(self, request, pk=None):
        articles = Article.objects.filter(magazine=self.kwargs.get('pk'))
        serializer = ArticleSerializer(articles, many=True)
        return Response(serializer.data, status=200)

这就是我尝试发送原始数据的方式：

{
    "title": "New Post form Postman",
    "content": "Postman content new",
    "magazine": [
        {
            "id": 1,
            "name": "The Times",
            "title": "All News"
        }
    ]
}

This is how I posted as form-data:

Answer 1

首先，您能否澄清一下您是否还希望从嵌套序列化程序中创建新的Magazine 对象，或者您是否希望用户只能为现有杂志创建Article（这似乎是您的第二次打电话给.exists())？

第一种情况：

如果您打算在第一种情况下，也希望在同一个 POST 请求中创建新杂志，我建议使用 drf-writeable-nested 包。

第二种情况：

为此，您也应该使用drf-writeable-nested 包。或者，您可以改用这个 hack：

from rest_framework.exceptions import ValidationError
from rest_framework import serializers
from .models import Article, Magazine

class ArticleSerializer(serializers.ModelSerializer):
    author = AuthorSerializer(read_only=True, many=False)
    magazines = MagazineSerializer(many=True, read_only=True)
    # accept list of PKs
    magazines_ids = serializers.PrimaryKeyRelatedField(
        many=True, write_only=True, queryset=Magazine.objects.all()
    )
    class Meta:
        model = Article
        fields = [
            'title',
            'content',
            'author',
            'magazines',
            'magazines_ids',
        ]

    def create(self, validated_data):
        magazines = validated_data.pop("magazines_ids", None)
        validated_data["author"] = self.context["request"].user
        article = Article.objects.create(**validated_data)
        if magazines:
            article.magazine.set(magazines)

        return article 

现在您的 POST 请求 JSON 正文应如下所示：

{
    "title": "New Post form Postman",
    "content": "Postman content new",
    "magazines_ids": [1]
}

magazines 参数获取主键列表。

---

奖金

另外，出于我的好奇，您确定要使用 ManytoManyField 吗？我会假设 Article 只能属于 single Magazine 您应该使用 ForeignKey，例如：

magazine = models.ForeignKey("articles.Magazine", related_name="articles")

然后在你的“行动”中，你可以做出这样的改变：

@action(detail=True, url_path='articles', url_name='articles')
def get_articles(self, request, pk=None):
    articles = self.get_object().articles
    serializer = ArticleSerializer(articles, many=True)
    return Response(serializer.data, status=200)