Question

我有2个型号：

from django.db import models

STATUSES = (
    ('f', 'Finished'),
)


class Battery(models.Model):
    energy = models.CharField(max_length=10)
    current = models.CharField(max_length=10)


class Charger(models.Model):
    status = models.CharField(max_length=1, choices=STATUSES)

我想创建序列化器，将这两个模型序列化在一起。我的serializers.py：

from rest_framework import serializers
from .models import Battery, Charger


class BatterySerializer(serializers.ModelSerializer):
    class Meta:
        model = Battery


class ChargerSerializer(serializers.ModelSerializer):
    status = serializers.SerializerMethodField()

    class Meta:
        model = Charger

    def get_status(self, obj):
        return obj.get_status_display()


class DeviceSerializer(serializers.Serializer):
    battery = BatterySerializer()
    charger = ChargerSerializer()
    some_field = serializers.CharField()

由于Charger模型在状态字段中有选择，我添加SerializerMethodField以显示完整状态。然后我创建一个这样的视图：

class DeviceView(APIView):
    def get(self, request, format=None):
        battery = Battery.objects.get(id=1)
        charger = Charger.objects.get(id=1)
        battery_serializer = BatterySerializer(battery)
        charger_serializer = ChargerSerializer(charger)
        serializer = DeviceSerializer(data={
            'battery': battery_serializer.data,
            'charger': charger_serializer.data,
            'some_field': 'some_text'
        })
        if serializer.is_valid():
            return Response(serializer.validated_data)
        else:
            return Response(status = 500)

但是当我调用此视图时，它返回带有空充电器字段的json：

{
    "battery": {
        "energy": "12",
        "current": "34"
    },
    "charger": {},
    "some_field": "some_text"
}

但是当我创建一个仅序列化Charger模型的视图时：

class ChargerView(APIView):
    def get(self, request, format=None):
        charger = Charger.objects.get(id=1)
        charger_serializer = ChargerSerializer(charger)
        return Response(charger_serializer.data)

它有效并返回此json：

{
    "id": 1,
    "status": "Finished"
}

为什么会这样？我在哪里弄错了？

Answer 1

查看Serializers的文档：

instance。 (link)
data。(link)
如果您有实例并且想要更新它，则会传递instance和data。(link)

考虑一下你的情况，我认为你不需要选项2和3，因为你有battery和charger个实例，你需要将它们序列化。您没有创建新实例，也不必验证它，因此不需要将其作为data传递。

有两种方法可以做到这一点：

1.创建一个类Device，以便您可以创建它的实例，然后使用DeviceSerializer对其进行序列化：

class Device(object):

    def __init__(self, battery, charger, some_field):
        self.battery = battery
        self.charger = charger
        self.some_field  = some_field

class DeviceView(APIView):
    # then in the DeviceView you could create an instance and pass to the serializer
    def get(self, request, format=None):
        battery = Battery.objects.get(id=1)
        charger = Charger.objects.get(id=1)
        device = Device(battery=battery, charger=charger, some_field='some_text')
        serializer = DeviceSerializer(instance=device)
        return Response(serializer.data)

2.如果您不想创建新课程，可以直接创建dict并将其作为实例传递：

class DeviceView(APIView):
    def get(self, request, format=None):
        battery = Battery.objects.get(id=1)
        charger = Charger.objects.get(id=1)
        # create a dict with required objects and pass it as instance of serializer
        device = {'battery': battery, 'charger': charger, 'some_field': 'some_text'}
        serializer = DeviceSerializer(instance=device)
        return Response(serializer.data)

Answer 2

好像你正在做你不必做的工作。如果您在将充电器传递到DeviceSerializer之前对其进行序列化，那么您实际上正在传递dict，而不是Charger个实例，dict没有{{} 1}}方法。您应该直接传递get_status_display和Battery：

Charger

请注意，您还可以使用CharField：

替换SerializerMethodField来简化

class DeviceView(APIView):
    def get(self, request, format=None):
        battery = Battery.objects.get(id=1)
        charger = Charger.objects.get(id=1)
        serializer = DeviceSerializer(instance={
            'battery': battery,
            'charger': charger,
            'some_field': 'some_text',
        })
        return Response(serializer.data)

编辑：正如AKS指出的那样，序列化时应该传递class ChargerSerializer(serializers.ModelSerializer): status = serializers.CharField(source='get_status_display') class Meta: model = Charger而不是instance序列化（data用于反序列化），并且您不需要检查data

Answer 3

在创建序列化程序实例时传递关键字数据，仅在反序列化数据时使用。您应该使用包含所需字段的对象创建DeviceSerializer。我没有测试过，但可能是这样的

class Device(object):
    def __init__(self, battery, charger, name, ):
        self.battery = battery
        self.charger = charger
        self.some_field = name

class DeviceView(APIView):
    def get(self, request, format=None):

        d=Device(Battery.objects.get(id=1),Charger.objects.get(id=1),"somename")
        serializer = DeviceSerializer(d)
            return Response(serializer.data)

Django Rest Framework没有序列化SerializerMethodField

3 个答案: