如何在Django模型中添加无需ForeignKey的对象字段

要实现你需要的pressure这类嵌套对象字段，核心是用Django的JSONField存储结构化数据，再通过DRF的序列化器将其处理成嵌套格式。下面分步骤给出可直接复用的代码示例：

1. 模型（Model）配置 #

用JSONField存储嵌套的pressure数据，它能直接保存字典结构，且支持后续的查询操作：

from django.db import models
import uuid

class Observation(models.Model):
    professional = models.UUIDField()  # 匹配示例中的UUID格式字符串
    observations = models.CharField(max_length=255)
    date = models.DateTimeField()
    # 初始化默认值，和你需要的结构一致
    pressure = models.JSONField(default=lambda: {"systolic_pressure": 0, "diastolic_pressure": 0})

2. 序列化器（Serializer）配置 #

推荐用子序列化器的方式处理嵌套结构，既能保证数据格式验证，又能自动生成你要的JSON结构：

from rest_framework import serializers
from .models import Observation

# 定义子序列化器，专门处理pressure的字段验证和格式转换
class PressureSerializer(serializers.Serializer):
    systolic_pressure = serializers.IntegerField(min_value=0)
    diastolic_pressure = serializers.IntegerField(min_value=0)

class ObservationSerializer(serializers.ModelSerializer):
    # 关联子序列化器，自动将JSON字典转为嵌套对象
    pressure = PressureSerializer()

    class Meta:
        model = Observation
        fields = ['id', 'professional', 'observations', 'date', 'pressure']

    def create(self, validated_data):
        # 直接用验证后的字典创建模型实例
        return Observation.objects.create(**validated_data)

    def update(self, instance, validated_data):
        # 单独处理pressure字段的更新
        instance.pressure = validated_data.get('pressure', instance.pressure)
        # 更新其他字段
        for field in ['professional', 'observations', 'date']:
            setattr(instance, field, validated_data.get(field, getattr(instance, field)))
        instance.save()
        return instance

如果不需要严格的字段验证，也可以简化为DictField：

class ObservationSerializer(serializers.ModelSerializer):
    pressure = serializers.DictField(child=serializers.IntegerField())

    class Meta:
        model = Observation
        fields = ['id', 'professional', 'observations', 'date', 'pressure']

3. 视图（View）配置 #

用DRF的ModelViewSet快速实现完整的增删改查（CRUD）操作：

from rest_framework import viewsets
from .models import Observation
from .serializers import ObservationSerializer

class ObservationViewSet(viewsets.ModelViewSet):
    queryset = Observation.objects.all()
    serializer_class = ObservationSerializer

4. URL路由配置 #

注册视图集，生成对应的CRUD接口：

from django.urls import path, include
from rest_framework.routers import DefaultRouter
from .views import ObservationViewSet

router = DefaultRouter()
router.register(r'observations', ObservationViewSet)

urlpatterns = [
    path('', include(router.urls)),
]

测试示例 #

发送POST请求到/observations/，请求体格式完全匹配你给出的示例：

{
    "professional": "d83876a6-69eb-4946-a0f7-56fd39cbd6a8",
    "observations": "Update",
    "date": "2022-03-22T21:45:37Z",
    "pressure": {
       "systolic_pressure": 120,
       "diastolic_pressure": 80
    }
}

GET请求返回的响应也会保持pressure的嵌套对象格式。

内容的提问来源于stack exchange，提问作者atbusch