support for setting default_image / default_flavor from tosca
diff --git a/xos/tosca/resources/slice.py b/xos/tosca/resources/slice.py
index e37bfc8..6227ec7 100644
--- a/xos/tosca/resources/slice.py
+++ b/xos/tosca/resources/slice.py
@@ -5,7 +5,7 @@
 sys.path.append("/opt/tosca")
 from translator.toscalib.tosca_template import ToscaTemplate
 
-from core.models import Slice,User,Site,Network,NetworkSlice,SliceRole,SlicePrivilege,Service
+from core.models import Slice,User,Site,Network,NetworkSlice,SliceRole,SlicePrivilege,Service,Image,Flavor
 
 from xosresource import XOSResource
 
@@ -26,6 +26,16 @@
             service = self.get_xos_object(Service, name=serviceName)
             args["service"] = service
 
+        default_image_name = self.get_requirement("tosca.relationships.DefaultImage", throw_exception=False)
+        if default_image_name:
+            default_image = self.get_xos_object(Image, name=default_image_name, throw_exception=True)
+            args["default_image"] = default_image
+
+        default_flavor_name = self.get_property_default("default_flavor", None)
+        if default_flavor_name:
+            default_flavor = self.get_xos_object(Flavor, name=default_flavor_name, throw_exception=True)
+            args["default_flavor"] = default_flavor
+
         return args
 
     def postprocess(self, obj):