如何使用 django rest 框架保存多对多字段对象

Posted 2023-02-24

【中文标题】如何使用 django rest 框架保存多对多字段对象

【英文标题】：How do i save many to many fields objects using django rest framework

【发布时间】：2017-01-17 05:39:30

【问题描述】：

我有三个模型博客、已发布、标签。在 Blogs 模型中，我将字段“postedin”作为 Posted 模型的外键，将“tags”字段作为 Tags 模型的 manytomany 字段。

models.py：

class Posted(models.Model):
    name = models.CharField(_('Posted In'),max_length=255, unique=True)

class Tags(models.Model):
    name = models.CharField(_('Tag Name'),max_length=255, unique=True)

class Blogs(models.Model):
    author = models.ForeignKey(CustomUser)
    title=models.CharField(max_length=100)
    postedin=models.ForeignKey(Posted)
    tags= models.ManyToManyField(Tags)
    content = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

views.py：

class BlogViewSet(viewsets.ModelViewSet):
    queryset=Blogs.objects.order_by('-created_at')
    serializer_class= BlogsSerializer

def get_permissions(self):
    if self.request.method in permissions.SAFE_METHODS:
        return (permissions.AllowAny(),)
    return (permissions.IsAuthenticated(),IsAuthorOfBlog())

def perform_create(self,serializer):

    serializer.save(author=self.request.user)

    return super(BlogViewSet,self).perform_create(serializer)

serializers.py:

class TagsSerializer(serializers.ModelSerializer):
    class Meta:
        model = Tags

        fields = ('pk','name')
        read_only_fields=('pk','name')

class PostedSerializer(serializers.ModelSerializer):
    class Meta:
        model = Posted

        fields = ('pk','name')
        read_only_fields=('pk','name')

class BlogsSerializer(serializers.ModelSerializer):
    author = AccountSerializer(read_only=True,required=False)
    tags=TagsSerializer(read_only=True,many=True)
    tags_id = serializers.PrimaryKeyRelatedField(queryset=Tags.objects.all(), write_only=True)
    postedin = PostedSerializer(read_only=True)
    postedin_id = serializers.PrimaryKeyRelatedField(queryset=Posted.objects.all(), write_only=True)

    class Meta:
        model = Blogs

        fields = ('pk','author','title','tags','tags_id','postedin','postedin_id','content','created_at','updated_at')
        read_only_fields=('pk','created_at','updated_at')


    def get_validation_exclusions(self, *args, **kwargs):
        exclusions = super(BlogsSerializer, self).get_validation_exclusions()

        return exclusions + ['author']
    def create(self, validated_data):
        postedin = validated_data.pop('postedin_id')
        tags = validated_data.pop('tags_id')
        blogs = Blogs.objects.create(tags=tags,postedin=postedin, **validated_data)
        return blogs

请求已发送：

标题：“nvnbv”，postedin_id：“1”，tags_id：[“2”，“5”，“1”，“4”]，内容：“nmvmvjm”

回复收到：

tags_id: ["类型不正确。预期的pk值，收到的列表。"]

我是 Django-rest-framework 的初学者。如何解决这个错误。

提前致谢！

【问题讨论】：

你试过serializers.PrimaryKeyRelatedField(queryset=Tags.objects.all(), write_only=True, many=True)吗？

@Abdulafaja 收到错误“'tags' is an invalid keyword argument for this function”

哪个函数？给出所有错误

@Abdulafaja。应用您的建议后。在'def create(self,validated_data)'函数中

docs.djangoproject.com/es/1.10/topics/db/examples/many_to_many 在创建博客之前您不能关联 ManyToMany 字段

【参考方案1】：

感谢@Abdulafaja 的建议。

终于找到解决办法了

BlogsSerializer 应该是

class BlogsSerializer(serializers.ModelSerializer):
    author = AccountSerializer(read_only=True,required=False)
    tags=TagsSerializer(read_only=True,many=True)
    tags_id = serializers.PrimaryKeyRelatedField(queryset=Tags.objects.all(), write_only=True,many=True)
    postedin = PostedSerializer(read_only=True)
    postedin_id = serializers.PrimaryKeyRelatedField(queryset=Posted.objects.all(), write_only=True)

    class Meta:
        model = Blogs

        fields = ('pk','author','title','tags','tags_id','postedin','postedin_id','content','created_at','updated_at')
        read_only_fields=('pk','created_at','updated_at')


    def get_validation_exclusions(self, *args, **kwargs):
        exclusions = super(BlogsSerializer, self).get_validation_exclusions()

        return exclusions + ['author']
    def create(self, validated_data):
        postedin = validated_data.pop('postedin_id')
        tags = validated_data.pop('tags_id')
        blogs = Blogs.objects.create(postedin=postedin, **validated_data)
        for tg in tags:
            blogs.tags.add(tg)
        return blogs

【参考方案2】：

不用循环，你可以简单地使用这一行blogs.tags.add(*tg)

def create(self, validated_data):
    postedin = validated_data.pop('postedin_id')
    tags = validated_data.pop('tags_id')
    blogs = Blogs.objects.create(postedin=postedin, **validated_data)
    blogs.tags.add(*tg)
    return blogs