Django REST Framework中高效选择与序列化模型字段的实践

from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from .models import PowerMeter # 假设你的模型定义在models.py中
from .serializers import VAndISerializer # 假设你的序列化器定义在serializers.py中

class VAndIAPIView(APIView): # 建议重命名视图类以避免与模型名称冲突
    def get(self, request):
        # 直接获取模型实例的查询集，不使用 .values()
        queryset = PowerMeter.objects.order_by('-id')[:5]

        # 将模型实例查询集传递给序列化器
        serializer = VAndISerializer(instance=queryset, many=True)
        return Response(serializer.data, status=status.HTTP_200_OK)

class VAndIAPIView(APIView):
    def get(self, request):
        # 使用 select_related() 预加载关联的 meter_id 对象
        # 假设 meter_id 是 PowerMeter 模型的一个 ForeignKey 字段
        queryset = PowerMeter.objects.select_related('meter_id').order_by('-id')[:5]
        serializer = VAndISerializer(instance=queryset, many=True)
        return Response(serializer.data, status=status.HTTP_200_OK)

from rest_framework import serializers

class DynamicFieldsModelSerializer(serializers.ModelSerializer):
    """
    一个ModelSerializer，接受一个额外的`fields`参数来控制显示哪些字段。
    """
    def __init__(self, *args, **kwargs):
        # 不将'fields'参数传递给父类
        fields = kwargs.pop('fields', None)

        # 正常实例化父类
        super().__init__(*args, **kwargs)

        if fields is not None:
            # 移除任何未在`fields`参数中指定的字段
            allowed = set(fields)
            existing = set(self.fields)
            for field_name in existing - allowed:
                self.fields.pop(field_name)

class VAndISerializer(DynamicFieldsModelSerializer):
    class Meta:
        model = PowerMeter
        # 这里定义了所有可能的字段。DynamicFieldsModelSerializer的__init__方法
        # 会在运行时根据传入的`fields`参数进行过滤。
        fields = ["id", "meter_id", "State", "date", "VII1", "VII2", "VII3", "VII_avg"]

class VAndIAPIView(APIView):
    def get(self, request):
        queryset = PowerMeter.objects.select_related('meter_id').order_by('-id')[:5]

        # 在实例化 VAndISerializer 时传入 fields 参数
        serializer = VAndISerializer(
            instance=queryset,
            many=True,
            fields=[
                'id',
                'meter_id',
                'State',
                'date',
                'VII1',
                'VII2',
                'VII3',
                'VII_avg',
            ],
        )
        return Response(serializer.data, status=status.HTTP_200_OK)