old_contents: from rest_framework.decorators import api_view
  from rest_framework.response import Response
  from rest_framework.reverse import reverse
  from rest_framework import serializers
  from rest_framework import generics
  from rest_framework import status
  from core.models import *
  from django.forms import widgets
  from services.cord.models import CordSubscriberRoot
  from services.vtr.models import VTRTenant, VTRService
  from xos.apibase import XOSListCreateAPIView, XOSRetrieveUpdateDestroyAPIView, XOSPermissionDenied
  from api.xosapi_helpers import PlusModelSerializer, XOSViewSet, ReadOnlyField
  
  def get_default_vtr_service():
      vtr_services = VTRService.get_service_objects().all()
      if vtr_services:
          return vtr_services[0].id
      return None
  
  class VTRTenantForAPI(VTRTenant):
      class Meta:
          proxy = True
          app_label = "cord"
  
  class VTRTenantSerializer(PlusModelSerializer):
          id = ReadOnlyField()
          target_id = serializers.IntegerField()
          test = serializers.CharField()
          scope = serializers.CharField()
          argument = serializers.CharField(required=False)
          provider_service = serializers.PrimaryKeyRelatedField(queryset=VTRService.get_service_objects().all(), default=get_default_vtr_service)
          result = serializers.CharField(required=False)
          result_code = serializers.CharField(required=False)
          backend_status = ReadOnlyField()
  
          humanReadableName = serializers.SerializerMethodField("getHumanReadableName")
          is_synced = serializers.SerializerMethodField("isSynced")
  
          class Meta:
              model = VTRTenantForAPI
              fields = ('humanReadableName', 'id', 'provider_service', 'target_id', 'scope', 'test', 'argument', 'result', 'result_code', 'is_synced', 'backend_status' )
  
          def getHumanReadableName(self, obj):
              return obj.__unicode__()
  
          def isSynced(self, obj):
              return (obj.enacted is not None) and (obj.enacted >= obj.updated)
  
  class TruckRollViewSet(XOSViewSet):
      base_name = "truckroll"
      method_name = "truckroll"
      method_kind = "viewset"
      queryset = VTRTenantForAPI.get_tenant_objects().all() # select_related().all()
      serializer_class = VTRTenantSerializer
  
      @classmethod
      def get_urlpatterns(self, api_path="^"):
          patterns = super(TruckRollViewSet, self).get_urlpatterns(api_path=api_path)
  
          return patterns
  
      def list(self, request):
          queryset = self.filter_queryset(self.get_queryset())
  
          serializer = self.get_serializer(queryset, many=True)
  
          return Response(serializer.data)
  
  
new_contents: from rest_framework.decorators import api_view
  from rest_framework.response import Response
  from rest_framework.reverse import reverse
  from rest_framework import serializers
  from rest_framework import generics
  from rest_framework import status
  from core.models import *
  from django.forms import widgets
  from services.cord.models import CordSubscriberRoot
  from services.vtr.models import VTRTenant, VTRService
  from xos.apibase import XOSListCreateAPIView, XOSRetrieveUpdateDestroyAPIView, XOSPermissionDenied
  from api.xosapi_helpers import PlusModelSerializer, XOSViewSet, ReadOnlyField
  
  def get_default_vtr_service():
      vtr_services = VTRService.get_service_objects().all()
      if vtr_services:
          return vtr_services[0]
      return None
  
  class VTRTenantForAPI(VTRTenant):
      class Meta:
          proxy = True
          app_label = "cord"
  
  class VTRTenantSerializer(PlusModelSerializer):
          id = ReadOnlyField()
          target_id = serializers.IntegerField()
          test = serializers.CharField()
          scope = serializers.CharField()
          argument = serializers.CharField(required=False)
          provider_service = serializers.PrimaryKeyRelatedField(queryset=VTRService.get_service_objects().all(), default=get_default_vtr_service)
          result = serializers.CharField(required=False)
          result_code = serializers.CharField(required=False)
          backend_status = ReadOnlyField()
  
          humanReadableName = serializers.SerializerMethodField("getHumanReadableName")
          is_synced = serializers.SerializerMethodField("isSynced")
  
          class Meta:
              model = VTRTenantForAPI
              fields = ('humanReadableName', 'id', 'provider_service', 'target_id', 'scope', 'test', 'argument', 'result', 'result_code', 'is_synced', 'backend_status' )
  
          def getHumanReadableName(self, obj):
              return obj.__unicode__()
  
          def isSynced(self, obj):
              return (obj.enacted is not None) and (obj.enacted >= obj.updated)
  
  class TruckRollViewSet(XOSViewSet):
      base_name = "truckroll"
      method_name = "truckroll"
      method_kind = "viewset"
      queryset = VTRTenantForAPI.get_tenant_objects().all() # select_related().all()
      serializer_class = VTRTenantSerializer
  
      @classmethod
      def get_urlpatterns(self, api_path="^"):
          patterns = super(TruckRollViewSet, self).get_urlpatterns(api_path=api_path)
  
          return patterns
  
      def list(self, request):
          queryset = self.filter_queryset(self.get_queryset())
  
          serializer = self.get_serializer(queryset, many=True)
  
          return Response(serializer.data)
  
  
subject: fix bug when getting default VTRService