old_contents: from core.models.user import AtmosphereUser
  from core.query import only_current
  from rest_framework import serializers
  from .application_serializer import ApplicationSerializer
  from .instance_serializer import InstanceSerializer
  from .volume_serializer import VolumeSerializer
  
  
  class NoProjectSerializer(serializers.ModelSerializer):
      applications = serializers.SerializerMethodField('get_user_applications')
      instances = serializers.SerializerMethodField('get_user_instances')
      volumes = serializers.SerializerMethodField('get_user_volumes')
  
      def get_user_applications(self, atmo_user):
          return [ApplicationSerializer(
              item,
              context={'request': self.context.get('request')}).data for item in
              atmo_user.application_set.filter(only_current(), projects=None)]
  
      def get_user_instances(self, atmo_user):
          return [InstanceSerializer(
              item,
              context={'request': self.context.get('request')}).data for item in
              atmo_user.instance_set.filter(only_current(),
                  source__provider__active=True,
                  projects=None)]
  
      def get_user_volumes(self, atmo_user):
          return [VolumeSerializer(
              item,
              context={'request': self.context.get('request')}).data for item in
              atmo_user.volume_set().filter(only_current(),
                  provider__active=True, projects=None)]
      class Meta:
          model = AtmosphereUser
          fields = ('applications', 'instances', 'volumes')
new_contents: from core.models.user import AtmosphereUser
  from core.query import only_current
  from rest_framework import serializers
  from .application_serializer import ApplicationSerializer
  from .instance_serializer import InstanceSerializer
  from .volume_serializer import VolumeSerializer
  
  
  class NoProjectSerializer(serializers.ModelSerializer):
      applications = serializers.SerializerMethodField('get_user_applications')
      instances = serializers.SerializerMethodField('get_user_instances')
      volumes = serializers.SerializerMethodField('get_user_volumes')
  
      def get_user_applications(self, atmo_user):
          return [ApplicationSerializer(
              item,
              context={'request': self.context.get('request')}).data for item in
              atmo_user.application_set.filter(only_current(), projects=None)]
  
      def get_user_instances(self, atmo_user):
          return [InstanceSerializer(
              item,
              context={'request': self.context.get('request')}).data for item in
              atmo_user.instance_set.filter(only_current(),
                  source__provider__active=True,
                  projects=None)]
  
      def get_user_volumes(self, atmo_user):
          return [VolumeSerializer(
              item,
              context={'request': self.context.get('request')}).data for item in
              atmo_user.volume_set().filter(only_current(),
                  provider__active=True, projects=None)]
  
      class Meta:
          model = AtmosphereUser
          fields = ('applications', 'instances', 'volumes')
subject: upgrade NoProjectSerializer to DRF3