Feriennet: Resolves n+1 queries for homepage

TYPE: Performance
LINK: None

Sentry examples:

    https://seantis-gmbh.sentry.io/issues/trace/0c49d7a3f0314d11acec7a2859f47232/
    https://seantis-gmbh.sentry.io/issues/trace/72578e382105402aac1ef2a6c37e056b/

Author: Tschuppi81

src/onegov/feriennet/homepage_widgets.py

@@ -1,9 +1,10 @@
 from __future__ import annotations
 
+from sqlalchemy.orm import selectinload
+
 from onegov.activity import ActivityFilter
 from onegov.feriennet import FeriennetApp, _
 
-
 from typing import TYPE_CHECKING
 
 from onegov.feriennet.collections import MatchCollection
@@ -68,21 +69,29 @@ def get_variables(self, layout: DefaultLayout) -> RenderData:
 
             activity_ids = (o.activity_id for o in occasions)
             unique_activity_ids = list(dict.fromkeys(activity_ids))[:6]
-            activities = VacationActivityCollection(layout.app.session()
-                                                    ).query(
-            ).filter(VacationActivity.id.in_(unique_activity_ids)).all()
+            activities = (
+                VacationActivityCollection(layout.app.session())
+                .query()
+                .options(selectinload(VacationActivity.occasions))
+                .filter(VacationActivity.id.in_(unique_activity_ids))
+                .all()
+            )
 
             if len(activities) < 6:
                 filter_obj = ActivityFilter()
                 filter_obj.period_ids = (
                 {layout.app.active_period.id
                  } if layout.app.active_period else set())
-                rest_activities = VacationActivityCollection(
-                    layout.app.session(),
-                    filter=filter_obj,
-                    ).query().filter(
-                    VacationActivity.id.notin_(unique_activity_ids)).limit(
-                        6 - len(activities))
+                rest_activities = (
+                    VacationActivityCollection(
+                        layout.app.session(),
+                        filter=filter_obj,
+                    )
+                    .query()
+                    .options(selectinload(VacationActivity.occasions))
+                    .filter(VacationActivity.id.notin_(unique_activity_ids))
+                    .limit(6 - len(activities))
+                )
                 activities = activities + rest_activities.all()
         else:
             activities = []