如何从 django 中的两个不同表中返回数据？

Question

我的 models.py 中有两个模型。我需要返回一个 json 响应，其中包含来自两个表的数据。 我的视图和序列化程序应该是什么样子？

class Device(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    device_name = models.CharField(max_length=200, null=True, blank=True )
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return str(self.device_name)

class StatusActivity(models.Model):
    OFFLINE = 1
    ONLINE = 2
    STATUS = (
        (OFFLINE, ('Offline')),
        (ONLINE, ('Online')),
    )
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    device_id = models.ForeignKey(Device, related_name='StatusActivity', on_delete=models.CASCADE)
    changed_to = models.PositiveSmallIntegerField(choices=STATUS)
    modified_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return str(self.device_id)

预期响应：

 {
    "device_id":"",
    "device_name":"",
    "changed_to":"",
    "modified_at":"",
  }

更新： 我将views.py 和serializer.py 设置如下。我正在检查

Serializer.py

class DeviceSerializer(serializers.ModelSerializer):
    class Meta:
        model = Device
        fields = '__all__'

class StatusActivitySerializer(serializers.ModelSerializer):

    class Meta:
        model = StatusActivity
        fields = '__all__'

class ListSerializer(serializers.Serializer):
    # devices = DeviceSerializer(many=True)
    # activities = StatusActivitySerializer(many=True)

    class Meta:
        model = [Device, StatusActivity]
        fields = ['device_id', 'device_name', 'changed_to', 'modified_at']

Views.py

class DeviceListView(generics.ListAPIView):
    queryset = Device.objects.all()
    serializer_class = ListSerializer

class StatusActivityListView(generics.ListAPIView):
    queryset = StatusActivity.objects.all()
    serializer_class = StatusActivitySerializer

Answer 1

过滤状态活动。你可以参考外键。 例如：

items = []
for statusact in StatusActivity.objects.all():
    items.append({
        "device_id":statusact.device_id.id,
        "device_name":statusact.device_id.device_name,
        "changed_to":statusact.changed_to,
        "modified_at":statusact.modified_at,
    })

Answer 2

实际上，您不需要为此设置两个单独的视图，因为您可以轻松地从一个序列化程序类中序列化关系。 看看这个有用的答案：How do I include related model fields using Django Rest Framework?

对于你的情况，你可以这样写：

class StatusActivitySerializer(serializers.ModelSerializer):
    device_name = serializers.CharField(source='device_id.device_name')

    class Meta:
        model = StatusActivity
        fields = ('changed_to', 'modified_at', 'device_id', 'device_name')

注意事项：

1. For ForeignKey 字段最好使用device 名称而不是 device_id;
2. related_name arg 应具有用于反向访问的名称。留着它 有意义的，例如status_activities 是个不错的选择。