only update params with values

datadog/dogshell/monitor.py

@@ -143,11 +143,12 @@ def _update(cls, args):
             to_update['type'] = args.type_opt
         if args.query_opt:
             to_update['query'] = args.query_opt
-
-        # these are not required for validation so no need to exclude if None
-        to_update['name'] = args.name
-        to_update['message'] = args.message
-        to_update['options'] = args.options
+        if args.name:
+            to_update['name'] = args.name
+        if args.message:
+            to_update['message'] = args.message
+        if args.options:
+            to_update['options'] = args.options
 
         res = api.Monitor.update(args.monitor_id, **to_update)