Django Rest Framework - 如何在序列化器中嵌套多个字段？

Question

我有几个基本模型,有几个控制字段.其中,位置字段由lat,lon,准确度,提供者和客户端时间组成.我的大多数可写模型(以及资源​​)都是从这个基础模型继承而来的.

我正在尝试让DRF在嵌套的"位置"字段中序列化与位置相关的字段.例如,

{
 "id": 1, 
 "name": "Some name",
 "location": { 
   "lat": 35.234234, 
   "lon": 35.234234,
   "provider": "network", 
   "accuracy": 9.4, 
 }
}

重要的是要记住这些字段是基本模型上的常规(平面)字段.

我调查过,发现了几个选择

1. 创建自定义字段,并通过覆盖"get_attribute"创建嵌套表示.我不喜欢这个解决方案,因为我失去了模型序列化器的一些好处,例如验证.

2. 创建名为Location的嵌套资源.我想我可以通过在模型上添加相同名称的属性来使其工作,但同样,没有验证.

所以我的问题是,在DRF序列化器中嵌套(或分组)多个字段的最佳方法是什么？

DRF 3.0.0,Django 1.7

编辑:

建立在@Tom Christie之上回答这是我提出的(简化)

# models.py
class BaseModel(models.Model):
  id = models.AutoField(primary_key=True)
  lat = models.FloatField(blank=True, null=True)
  lon = models.FloatField(blank=True, null=True)
  location_time = models.DateTimeField(blank=True, null=True)
  location_accuracy = models.FloatField(blank=True, null=True)
  location_provider = models.CharField(max_length=50, blank=True, null=True)

  @property
  def location(self):
    return {
      'lat': self.lat,
      'lon': self.lon,
      'location_time': self.location_time,
      'location_accuracy': self.location_accuracy,
      'location_provider': self.location_provider
    }

class ChildModel(BaseModel):
  name = models.CharField(max_lengtg=10)


# serializers.py
class LocationSerializer(serializers.Serializer):
  lat = serializers.FloatField(allow_null=True, required=False)
  lon = serializers.FloatField(allow_null=True, required=False)
  location_time = serializers.DateTimeField(allow_null=True, required=False)
  location_accuracy = serializers.FloatField(allow_null=True, required=False)
  location_provider = serializers.CharField(max_length=50,allow_null=True, required=False)


class BaseSerializer(serializers.ModelSerializer):

  def create(self,validated_data):
    validated_data.update(validated_data.pop('location',{}))
    return super(BaseSerializer,self).create(validated_data)

  def update(self, instance, validated_data):
    location = LocationSerializer(data=validated_data.pop('location',{}), partial=True)
    if location.is_valid():
      for attr,value in location.validated_data.iteritems():
        setattr(instance,attr,value)
    return super(BaseSerializer,self).update(instance, validated_data)

class ChildSerializer(BaseSerializer):
    location = LocationSerializer()

    class meta:
      model = ChildModel
      fields = ('name','location',)

我已经测试了有效/无效的帖子/补丁,它运作得很好.

谢谢.

Answer 1

我建议只使用显式的序列化程序类,并明确地编写字段.它有点冗长,但它简单,明显且易于维护.

class LocationSerializer(serializers.Serializer):
    lat = serializers.FloatField()
    lon = serializers.FloatField()
    provider = serializers.CharField(max_length=100)
    accuracy = serializers.DecimalField(max_digits=3, decimal_places=1)

class FeatureSerializer(serializers.Serializer):
    name = serializers.CharField(max_length=100)
    location = LocationSerializer()

    def create(self, validated_data):
        return Feature.objects.create(
            name=validated_data['name'],
            lat=validated_data['location']['lat'],
            lon=validated_data['location']['lat'],
            provider=validated_data['location']['provider'],
            accuracy=validated_data['location']['accuracy']
        )

    def update(self, instance, validated_data):
        instance.name = validated_data['name']
        instance.lat = validated_data['location']['lat']
        instance.lon = validated_data['location']['lat']
        instance.provider = validated_data['location']['provider']
        instance.accuracy = validated_data['location']['accuracy']
        instance.save()
        return instance

有很多方法你可以使用ModelSerializer替代,或者方法来保持create和update方法稍微短一些,但是不清楚你自己给予的额外间接是否值得.

我们几乎总是使用完全显式的序列化器类来处理我们正在构建的API.