fix(graphql): Optimize N+1 queries for events

graphene_linked_events/schema.py

@@ -466,8 +466,10 @@ def _test_events_p_event_relations(events_json):
         events = json.loads(events_json, object_hook=lambda d: SimpleNamespace(**d))
 
         # Get related palvelutarjotin events
-        p_events = PalvelutarjotinEvent.objects.prefetch_related("occurrences").filter(
-            linked_event_id__in=[e.id for e in events.data]
+        p_events = (
+            PalvelutarjotinEvent.objects.select_related("organisation")
+            .prefetch_related("occurrences")
+            .filter(linked_event_id__in=[e.id for e in events.data])
         )
 
         # Prune a list of events which have a link to a palvelutarjotin event

occurrences/models.py

@@ -304,17 +304,25 @@ def has_space_for_enrolments(self) -> Optional[bool]:
         if not self.has_enrolments_system() or self.has_external_enrolments_system():
             return None
 
-        has_upcoming_space = any(
-            occurrence.has_space_left()
-            for occurrence in self.occurrences.filter_upcoming()
-        )
+        now = timezone.now()
+        # Use prefetched occurrences (.all()) to avoid extra DB queries per event.
+        all_occurrences = list(self.occurrences.all())
+
+        upcoming = [
+            o
+            for o in all_occurrences
+            if not o.cancelled and o.start_time >= now
+        ]
+        has_upcoming_space = any(o.has_space_left() for o in upcoming)
 
         if self.enrolment_end_days is None:
             # No limit to when enrolments can be made before the occurrence start.
-            return has_upcoming_space or any(
-                occurrence.has_space_left()
-                for occurrence in self.occurrences.filter_ongoing()
-            )
+            ongoing = [
+                o
+                for o in all_occurrences
+                if not o.cancelled and o.start_time <= now and o.end_time >= now
+            ]
+            return has_upcoming_space or any(o.has_space_left() for o in ongoing)
 
         return has_upcoming_space
 

occurrences/schema.py

@@ -200,22 +200,23 @@ class Meta:
         interfaces = (graphene.relay.Node,)
 
     def resolve_next_occurrence_datetime(self, info, **kwargs):
-        try:
-            return (
-                self.occurrences.filter(start_time__gte=timezone.now(), cancelled=False)
-                .earliest("start_time")
-                .start_time
-            )
-        except Occurrence.DoesNotExist:
+        # Filter the prefetched occurrences in Python to avoid extra DB queries.
+        now = timezone.now()
+        upcoming = [
+            o
+            for o in self.occurrences.all()
+            if not o.cancelled and o.start_time >= now
+        ]
+        if not upcoming:
             return None
+        return min(upcoming, key=lambda o: o.start_time).start_time
 
     def resolve_last_occurrence_datetime(self, info, **kwargs):
-        try:
-            return (
-                self.occurrences.filter(cancelled=False).latest("start_time").start_time
-            )
-        except Occurrence.DoesNotExist:
+        # Filter the prefetched occurrences in Python to avoid extra DB queries.
+        non_cancelled = [o for o in self.occurrences.all() if not o.cancelled]
+        if not non_cancelled:
             return None
+        return max(non_cancelled, key=lambda o: o.start_time).start_time
 
     def resolve_has_space_for_enrolments(self, info, **kwargs):
         """