From f792b808c14246a524a82017595d44f7efaeeab6 Mon Sep 17 00:00:00 2001
From: Valentin Deniaud <vdeniaud@entrouvert.com>
Date: Thu, 11 Mar 2021 12:00:43 +0100
Subject: [PATCH 1/2] manager: use slug instead of start_datetime to identify
 event recurrence (#52112)

---
 chrono/agendas/models.py | 9 ++++++++-
 chrono/manager/forms.py  | 5 +----
 tests/test_manager.py    | 9 +++++++++
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/chrono/agendas/models.py b/chrono/agendas/models.py
index b25a954..0ccc88c 100644
--- a/chrono/agendas/models.py
+++ b/chrono/agendas/models.py
@@ -616,7 +616,7 @@ class Agenda(models.Model):
         excluded_datetimes = collections.defaultdict(list)
         for event in events:
             if event.primary_event_id:
-                excluded_datetimes[event.primary_event_id].append(make_naive(event.start_datetime))
+                excluded_datetimes[event.primary_event_id].append(event.datetime_slug)
 
         events = [
             e for e in events if (not e.cancelled or include_cancelled) and (not e.full or include_full)
@@ -1436,6 +1436,13 @@ class Event(models.Model):
         recurrences = self.get_recurrences(localtime(now()), make_aware(max_datetime), excluded_datetimes)
         Event.objects.bulk_create(recurrences)
 
+    @property
+    def datetime_slug(self):
+        assert self.primary_event is not None, 'only for event recurrence'
+
+        datetime_part = self.slug.rsplit('--')[-1]
+        return datetime.datetime.strptime(datetime_part, '%Y-%m-%d-%H%M')
+
 
 class BookingColor(models.Model):
     COLOR_COUNT = 8
diff --git a/chrono/manager/forms.py b/chrono/manager/forms.py
index 5a6c5fa..5b240ee 100644
--- a/chrono/manager/forms.py
+++ b/chrono/manager/forms.py
@@ -241,10 +241,7 @@ class EventForm(forms.ModelForm):
                 self.instance.recurrences.filter(
                     start_datetime__gt=self.instance.recurrence_end_date
                 ).delete()
-                excluded_datetimes = [
-                    make_naive(dt)
-                    for dt in self.instance.recurrences.values_list('start_datetime', flat=True)
-                ]
+                excluded_datetimes = [event.datetime_slug for event in self.instance.recurrences.all()]
                 self.instance.create_all_recurrences(excluded_datetimes)
         return self.instance
 
diff --git a/tests/test_manager.py b/tests/test_manager.py
index 6e5a19e..eb321d5 100644
--- a/tests/test_manager.py
+++ b/tests/test_manager.py
@@ -1618,6 +1618,15 @@ def test_edit_recurring_event_with_end_date(settings, app, admin_user, freezer):
     # old recurrences were deleted
     assert not Event.objects.filter(primary_event=event, start_datetime=now()).exists()
 
+    # if start datetime of a recurrence is edited, it stays that way
+    recurrence = event.recurrences.first()
+    recurrence.start_datetime += datetime.timedelta(hours=1)
+    recurrence.save()
+    resp = app.get('/manage/agendas/%s/events/%s/edit' % (agenda.id, event.id))
+    resp = resp.form.submit()
+    assert Event.objects.filter(primary_event=event).count() == 5
+    assert Event.objects.filter(primary_event=event, start_datetime=recurrence.start_datetime).count() == 1
+
     # editing recurrence_end_date is permitted as long as bookings are not impacted
     event_recurrence = Event.objects.get(primary_event=event, start_datetime__day=15)
     Booking.objects.create(event=event_recurrence)
-- 
2.20.1