From 7032b8c7c78f33c5e1065b314a1a07ddc32533c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Kucharczyk?= <lukas@kucharczyk.xyz>
Date: Tue, 30 Dec 2025 13:24:09 +0100
Subject: [PATCH] Fix signals interfering with deleting a game with sessions

---
 games/signals.py      | 10 +++++++++-
 tests/test_signals.py | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_signals.py

diff --git a/games/signals.py b/games/signals.py
index 9728354..fcd4894 100644
--- a/games/signals.py
+++ b/games/signals.py
@@ -20,7 +20,15 @@ def update_num_purchases(sender, instance, **kwargs):
 
 @receiver([post_save, post_delete], sender=Session)
 def update_game_playtime(sender, instance, **kwargs):
-    game = instance.game
+    # During cascade deletes the related Game may already have been removed.
+    # Use the FK id to look up the Game safely and bail out if it no longer exists.
+    game_pk = getattr(instance, "game_id", None)
+    if not game_pk:
+        return
+    game = Game.objects.filter(pk=game_pk).first()
+    if not game:
+        return
+
     total_playtime = game.sessions.aggregate(
         total_playtime=Sum(F("duration_calculated") + F("duration_manual"))
     )["total_playtime"]
diff --git a/tests/test_signals.py b/tests/test_signals.py
new file mode 100644
index 0000000..2070dd6
--- /dev/null
+++ b/tests/test_signals.py
@@ -0,0 +1,39 @@
+import os
+from datetime import datetime
+from zoneinfo import ZoneInfo
+
+import django
+from django.test import TestCase
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "timetracker.settings")
+django.setup()
+from django.conf import settings
+
+from games.models import Game, Session
+
+ZONEINFO = ZoneInfo(settings.TIME_ZONE)
+
+
+class SignalsTest(TestCase):
+    def test_deleting_game_with_sessions_does_not_raise(self):
+        # Create a game and attach a session to it
+        g = Game(name="Signal Test Game")
+        g.save()
+
+        s = Session(
+            game=g,
+            timestamp_start=datetime(2022, 9, 26, 14, 58, tzinfo=ZONEINFO),
+            timestamp_end=datetime(2022, 9, 26, 17, 38, tzinfo=ZONEINFO),
+        )
+        s.save()
+
+        # Sanity checks before delete
+        self.assertTrue(Game.objects.filter(pk=g.pk).exists())
+        self.assertEqual(g.sessions.count(), 1)
+
+        # Deleting the game should not raise (signals run during cascade)
+        g.delete()
+
+        # After deletion, the Game should be gone and no sessions remain
+        self.assertFalse(Game.objects.filter(pk=g.pk).exists())
+        self.assertEqual(Session.objects.filter(pk=s.pk).count(), 0)