Fixed an issue in porting services to xproto

Change-Id: Ib850a2a5ad6310ba7ea979c7fc848a2481d0c0c9
diff --git a/xos/tools/apigen/modelgen2 b/xos/tools/apigen/modelgen2
index 5e16a28..916fbe5 100755
--- a/xos/tools/apigen/modelgen2
+++ b/xos/tools/apigen/modelgen2
@@ -211,9 +211,9 @@
 		self[str(obj).lower()]=obj
 
 	def compute_links(self):
-                base_props = [f.name for f in PlCoreBase._meta.fields] + ['id']
 
 		for obj in self.values():
+                	base_props = [f.name for f in obj.model.__base__._meta.fields] + ['id']
 			#if (str(obj)=='network'):
 			#	pdb.set_trace()
 			fields = obj.model._meta.fields