如何通过Django REST Framework序列化多张无关表生成合并JSON输出

问题背景 #

我正在开发一个订单管理系统，场景如下：用户可创建多种类型的订单，这些订单类型相互独立，但用户需要查看所有类型的订单。目前已在models.py中为每种订单类型创建了独立的数据表：

class OrderType1(models.Model):
    create_time = models.DateTimeField(auto_now_add=True, verbose_name="create_time")
    ordertype1_info = models.CharField(max_length=32, verbose_name="Exclusive info for OrderType1")

class OrderType2(models.Model):
    create_time = models.DateTimeField(auto_now_add=True, verbose_name="create_time")
    ordertype2_info = models.CharField(max_length=32, verbose_name="Exclusive info for OrderType2")

class OrderType3(models.Model):
    create_time = models.DateTimeField(auto_now_add=True, verbose_name="create_time")
    ordertype3_info = models.CharField(max_length=32, verbose_name="Exclusive info for OrderType3")

同时在serializers.py中对应创建了序列化器：

class OrderType1Serializer(serializers.ModelSerializer):
    class Meta:
        model = OrderType1
        fields="__all__"

class OrderType2Serializer(serializers.ModelSerializer):
    class Meta:
        model = OrderType2
        fields="__all__"

class OrderType3Serializer(serializers.ModelSerializer):
    class Meta:
        model = OrderType3
        fields="__all__"

核心需求是：创建一个能返回所有类型订单的序列化逻辑，最终返回的JSON格式如下：

{
    "OrderType1":[
        {
            "id": 1,
            "create_time": "2018-01-01 12:00:00",
            "ordertype1_info": "Exclusive info for OrderType1"
        },
        {
            "id": 2,
            "create_time": "2019-12-01 12:00:00",
            "ordertype1_info": "Exclusive info for OrderType1"
        }
    ],
    "OrderType2":[
        {
            "id": 1,
            "create_time": "2020-01-01 12:00:00",
            "ordertype2_info": "Exclusive info for OrderType2"
        }
    ],
    "OrderType3":[
        {
            "id": 1,
            "create_time": "2021-01-01 09:00:00",
            "ordertype3_info": "Exclusive info for OrderType3"
        },
        {
            "id": 2,
            "create_time": "2022-12-01 10:00:00",
            "ordertype3_info": "Exclusive info for OrderType3"
        },
        {
            "id": 3,
            "create_time": "2022-12-01 10:20:30",
            "ordertype3_info": "Exclusive info for OrderType3"
        }
    ]
}

解决方案 #

由于DRF的ModelSerializer只能绑定单个模型，无法直接实现多模型的序列化，推荐以下两种实现方式：

方式一：视图层聚合数据（推荐） #

直接在视图中查询各类型订单数据，用对应序列化器处理后组装成目标格式，代码简洁易维护：

# views.py
from rest_framework.views import APIView
from rest_framework.response import Response
from .models import OrderType1, OrderType2, OrderType3
from .serializers import OrderType1Serializer, OrderType2Serializer, OrderType3Serializer

# 定义订单类型与序列化器的映射，后续新增类型只需在此添加
ORDER_TYPE_MAPPING = [
    (OrderType1, OrderType1Serializer, "OrderType1"),
    (OrderType2, OrderType2Serializer, "OrderType2"),
    (OrderType3, OrderType3Serializer, "OrderType3"),
]

class AllOrdersView(APIView):
    def get(self, request):
        response_data = {}
        # 循环处理每种订单类型
        for model, serializer_cls, key in ORDER_TYPE_MAPPING:
            queryset = model.objects.all()
            response_data[key] = serializer_cls(queryset, many=True).data
        return Response(response_data)

方式二：自定义序列化器 #

通过继承DRF的Serializer自定义一个统一序列化器，在to_representation方法中完成数据查询与组装：

# serializers.py
from rest_framework import serializers
from .models import OrderType1, OrderType2, OrderType3
from .serializers import OrderType1Serializer, OrderType2Serializer, OrderType3Serializer

class AllOrdersSerializer(serializers.Serializer):
    def to_representation(self, instance):
        # 查询并序列化所有类型订单
        order1_data = OrderType1Serializer(OrderType1.objects.all(), many=True).data
        order2_data = OrderType2Serializer(OrderType2.objects.all(), many=True).data
        order3_data = OrderType3Serializer(OrderType3.objects.all(), many=True).data
        
        return {
            "OrderType1": order1_data,
            "OrderType2": order2_data,
            "OrderType3": order3_data
        }

对应的视图实现：

# views.py
from rest_framework.views import APIView
from rest_framework.response import Response
from .serializers import AllOrdersSerializer

class AllOrdersView(APIView):
    def get(self, request):
        serializer = AllOrdersSerializer(instance=None)
        return Response(serializer.data)

补充说明 #

• 两种方式都能实现需求，方式一更灵活，后续新增订单类型只需修改ORDER_TYPE_MAPPING列表即可，无需改动核心逻辑。
• 如果需要添加过滤、分页等功能，可在视图中对每个queryset进行对应的处理后再序列化。

内容的提问来源于stack exchange，提问作者user277104