add subnet_id field to slice model
diff --git a/plstackapi/core/serializers.py b/plstackapi/core/serializers.py
index ded1859..e9dc526 100644
--- a/plstackapi/core/serializers.py
+++ b/plstackapi/core/serializers.py
@@ -65,6 +65,7 @@
                   'slice_url',
                   'network_id',
                   'router_id',
+                  'subnet_id',
                   'site',
                   'slivers',
                   'updated',