fix(grist): Don't send request to grist of nothing is written

src/meal_manager/grist.py

@@ -14,7 +14,11 @@ config = {
 }
 
 
-def sync_with_grist(event):
+def sync_with_grist(event) -> int:
+    """Writes the event's registrations to Grist.
+    If a registration already exists for a given household, it is not overwritten.
+    Returns the number of new records.
+    """
     grist = GristApi(config=config)
 
     status_code, grist_response = grist.list_records(
@@ -53,4 +57,8 @@ def sync_with_grist(event):
                     "meal_manager_event_id": event.id,
                 }
             )
-    grist.add_records("Transactions", new_records)
+    if new_records:
+        grist.add_records("Transactions", new_records)
+        return len(new_records)
+    else:
+        return 0

src/meal_manager/main.py

@@ -4,6 +4,7 @@ from contextlib import asynccontextmanager
 from datetime import datetime, timedelta
 from functools import partial
 from typing import Annotated
+from urllib.parse import quote_plus
 
 import starlette.status as status
 from fastapi import Depends, FastAPI, HTTPException, Request, Response
@@ -446,9 +447,11 @@ def sync_with_grist_route(event_id: int, session: SessionDep, user: StrictUserDe
     statement = select(Event).where(Event.id == event_id)
     event = session.scalars(statement).one()
 
-    sync_with_grist(event)
-
+    entries_written = sync_with_grist(event)
+    message = "Es wurden keine Einträge geschrieben."
+    if entries_written > 0:
+        message = f"Erfolgreich {entries_written} Einträge geschrieben."
     return RedirectResponse(
-        url=f"/event/{event_id}?message=Erfolgreich%20an%20Abrechnung%20%C3%BCbertragen",
+        url=f"/event/{event_id}?message={quote_plus(message)}",
         status_code=status.HTTP_302_FOUND,
     )