python - Django REST Framework 验证 slug 字段

Question

我定义了这样一个序列化器:

class ActivitySerializer(serializers.ModelSerializer):
      activity_project = serializers.SlugRelatedField(queryset=Project.objects.all(), slug_field='project_name')

activity_tags = serializers.SlugRelatedField(queryset=Tag.objects.all(), slug_field='tag_name', many=True)
class Meta:
    model = Activity
    fields = ('activity_name', 'activity_description', 'activity_status', 'activity_completion_percent', 'activity_due_date', 'activity_project', 'activity_tags',)

现在如果我插入数据库中不存在的 activity_tag，我会收到验证错误"

{
    "activity_tags": [
        "Object with tag_name=test does not exist."
    ]
}

我想创建一个验证方法，如果标签不存在则将其添加到数据库中。我试过使用

def validate(self, attrs): 
    ....

方法，但显然对于 slug 字段，有一个方法在此之前被调用。

有人能指出我应该使用的正确方法吗？这个方法会在相应的 View 中被调用吗？

Answer 1

我认为您需要创建一个嵌套的序列化程序才能使其工作。这完全未经测试并且超出了我的脑海，但也许是这样的:

class ActivityTagFieldSerializer(serializer.ModelSerializer):
    tag_name = serializers.SlugField()
    class Meta:
        model = Tag
        fields = ('tag_name')

class ActivitySerializer(serializer.ModelSerializer):
    activity_tags = ActivityTagFieldSerializer(many=True)
    class Meta:
        model = Activity
        fields = ('activity_tags', 'activity_project', ...)

    def create(self, validated_data):
        tags = validated_data.pop('activity_tags')
        activity = Activity.objects.create(**validated_data)
        for tag in tags:
            try:
                tag_to_add = Tag.objects.get(**tag)
            except:
                tag_to_add = Tag.objects.create(**tag)
            activity.activity_tags.add(tag_to_add)
        return activity

查看 writable nested serializers 的 API 指南