api: reduce datetimes querysets (#56046)

chrono/agendas/models.py

@@ -1718,7 +1718,7 @@ class Event(models.Model):
 
     @property
     def datetime_slug(self):
-        assert self.primary_event is not None, 'only for event recurrence'
+        assert self.primary_event_id is not None, 'only for event recurrence'
 
         datetime_part = self.slug.rsplit('--')[-1]
         return datetime.datetime.strptime(datetime_part, '%Y-%m-%d-%H%M')

chrono/api/views.py

@@ -436,7 +436,7 @@ def get_event_text(event, agenda, day=None):
             )
         except (VariableDoesNotExist, TemplateSyntaxError):
             pass
-    elif event.label and event.primary_event is not None:
+    elif event.label and event.primary_event_id is not None:
         event_text = '%s (%s)' % (
             event.label,
             date_format(localtime(event.start_datetime), 'DATETIME_FORMAT'),

tests/api/test_datetimes.py

@@ -2,7 +2,9 @@ import datetime
 import urllib.parse as urlparse
 
 import pytest
+from django.db import connection
 from django.test import override_settings
+from django.test.utils import CaptureQueriesContext
 from django.utils.timezone import localtime, make_aware, now
 
 from chrono.agendas.models import Agenda, Booking, Desk, Event, TimePeriodException
@@ -654,6 +656,17 @@ def test_recurring_events_api(app, user, freezer):
     resp = app.get('/api/agenda/%s/datetimes/' % agenda.slug)
     assert resp.json['data'][0]['text'] == "Rock'n roll - Jan. 19, 2021, 1:05 p.m."
 
+    # check querysets
+    agenda.event_display_template = ''
+    agenda.save()
+    base_event.publication_date = None
+    base_event.recurrence_end_date = datetime.date.today() + datetime.timedelta(days=365)
+    base_event.save()
+    base_event.create_all_recurrences()
+    with CaptureQueriesContext(connection) as ctx:
+        app.get('/api/agenda/%s/datetimes/' % agenda.slug)
+        assert len(ctx.captured_queries) == 5
+
 
 def test_recurring_events_api_various_times(app, user, mock_now):
     agenda = Agenda.objects.create(