From 2cee74eb817669babb868c11870014f46c354bf9 Mon Sep 17 00:00:00 2001
From: Eu Pin Tien <eu-pin.tien@diamond.ac.uk>
Date: Fri, 13 Jun 2025 14:48:08 +0100
Subject: [PATCH] Fixed logic when passing empty datetime field to instrument
 server in 'setup_multigrid_watcher'

---
 src/murfey/server/api/instrument.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/murfey/server/api/instrument.py b/src/murfey/server/api/instrument.py
index 10a6244d3..970f963c5 100644
--- a/src/murfey/server/api/instrument.py
+++ b/src/murfey/server/api/instrument.py
@@ -127,7 +127,9 @@ async def setup_multigrid_watcher(
                         str(k): v for k, v in watcher_spec.destination_overrides.items()
                     },
                     "rsync_restarts": watcher_spec.rsync_restarts,
-                    "visit_end_time": str(session.visit_end_time),
+                    "visit_end_time": (
+                        str(session.visit_end_time) if session.visit_end_time else None
+                    ),
                 },
                 headers={
                     "Authorization": f"Bearer {instrument_server_tokens[session_id]['access_token']}"