From c9265aab68f26b28a0ca9df479994fbdff1ca56d Mon Sep 17 00:00:00 2001
From: Rebecca Law <rebecca.law@digital.cabinet-office.gov.uk>
Date: Wed, 1 May 2019 15:07:59 +0100
Subject: [PATCH] Don't do anything if the query doesn't yield results.

---
 app/dao/notifications_dao.py | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/app/dao/notifications_dao.py b/app/dao/notifications_dao.py
index 9d28ceeb8..f21d6fff7 100644
--- a/app/dao/notifications_dao.py
+++ b/app/dao/notifications_dao.py
@@ -395,21 +395,22 @@ def insert_update_notification_history(notification_type, date_to_delete_from, s
         Notification.key_type != KEY_TYPE_TEST
     ).all()
 
-    stmt = insert(NotificationHistory).values(
-        notifications
-    )
+    if notifications:
+        stmt = insert(NotificationHistory).values(
+            notifications
+        )
 
-    stmt = stmt.on_conflict_do_update(
-        constraint="notification_history_pkey",
-        set_={"notification_status": stmt.excluded.status,
-              "billable_units": stmt.excluded.billable_units,
-              "updated_at": stmt.excluded.updated_at,
-              "sent_at": stmt.excluded.sent_at,
-              "sent_by": stmt.excluded.sent_by
-              }
-    )
-    db.session.connection().execute(stmt)
-    db.session.commit()
+        stmt = stmt.on_conflict_do_update(
+            constraint="notification_history_pkey",
+            set_={"notification_status": stmt.excluded.status,
+                  "billable_units": stmt.excluded.billable_units,
+                  "updated_at": stmt.excluded.updated_at,
+                  "sent_at": stmt.excluded.sent_at,
+                  "sent_by": stmt.excluded.sent_by
+                  }
+        )
+        db.session.connection().execute(stmt)
+        db.session.commit()
 
 
 def _delete_letters_from_s3(