old_contents: from rest_framework import serializers
  from utils.serializers import ObjectTypeModelSerializer
  from . models import GCMDevice, GCMMessage
  
  
  class GCMDeviceSerializer(ObjectTypeModelSerializer):
      """A Serializer for the `GCMDevice` model."""
  
      class Meta:
          model = GCMDevice
          fields = (
              'id', 'user','device_name', 'device_id', 'registration_id',
              'is_active', 'created_on', 'updated_on',
          )
          read_only_fields = ("id", "created_on", "updated_on")
  
  
  class GCMMessageSerializer(ObjectTypeModelSerializer):
      """A Serializer for the `GCMMessage` model."""
  
      class Meta:
          model = GCMMessage
          fields = (
              'id', 'user', 'content', 'success', 'response_code',
              'deliver_on', 'created_on',
          )
  
new_contents: from rest_framework import serializers
  from utils.serializers import ObjectTypeModelSerializer
  from . models import GCMDevice, GCMMessage
  
  
  class GCMDeviceSerializer(ObjectTypeModelSerializer):
      """A Serializer for the `GCMDevice` model."""
  
      class Meta:
          model = GCMDevice
          fields = (
              'id', 'user','device_name', 'device_id', 'registration_id',
              'is_active', 'created_on', 'updated_on', 'oject_type',
          )
          read_only_fields = ("id", "created_on", "updated_on")
  
  
  class GCMMessageSerializer(ObjectTypeModelSerializer):
      """A Serializer for the `GCMMessage` model."""
  
      class Meta:
          model = GCMMessage
          fields = (
              'id', 'user', 'content', 'success', 'response_code',
              'deliver_on', 'created_on', 'object_type',
          )
  
subject: include object_types in the api