[FIX] calendar: prevent userError when base_event is not defined

Before this commit, the follwing traceback was sometimes raised.

Error message
ERROR: TestCalendar.test_event_creation_mail
Traceback (most recent call last):
  File "/data/build/odoo/addons/calendar/tests/test_calendar.py", line 339, in test_event_creation_mail
    m.write({
  File "/data/build/odoo/addons/calendar/models/calendar_event.py", line 574, in write
    self._rewrite_recurrence(values, time_values, recurrence_values)
  File "/data/build/odoo/addons/calendar/models/calendar_event.py", line 1084, in _rewrite_recurrence
    update_dict = self._get_time_update_dict(base_event, time_values)
  File "/data/build/odoo/addons/calendar/models/calendar_event.py", line 993, in _get_time_update_dict
    raise UserError(_("You can't update a recurrence without base event."))
odoo.exceptions.UserError: You can't update a recurrence without base event.

closes odoo#139486

X-original-commit: bd1c46a
Signed-off-by: Arnaud Joset (arj) <arj@odoo.com>

addons/calendar/models/calendar_event.py

@@ -1150,7 +1150,8 @@ def _update_future_events(self, values, time_values, recurrence_values):
             deactivate the detached events except for the updated event and apply recurrence values.
         """
         self.ensure_one()
-        update_dict = self._get_time_update_dict(self, time_values)
+        base_event = self
+        update_dict = self._get_time_update_dict(base_event, time_values)
         time_values.update(update_dict)
         # Get base values from the previous recurrence and update the start date weekday field.
         start_date = time_values['start'].date() if 'start' in time_values else self.start.date()
@@ -1183,7 +1184,7 @@ def _update_future_events(self, values, time_values, recurrence_values):
     def _rewrite_recurrence(self, values, time_values, recurrence_values):
         """ Delete the current recurrence, reactivate base event and apply updated recurrence values. """
         self.ensure_one()
-        base_event = self.recurrence_id.base_event_id
+        base_event = self.recurrence_id.base_event_id or self.recurrence_id._get_first_event(include_outliers=False)
         update_dict = self._get_time_update_dict(base_event, time_values)
         time_values.update(update_dict)
 

addons/calendar/tests/test_calendar.py

@@ -316,15 +316,14 @@ def _test_one_mail_per_attendee(self, partners):
             self.env['res.partner'].create({'name': 'testuser1', 'email': u'alice@example.com'}),
         ]
         partner_ids = [(6, False, [p.id for p in partners]),]
-        now = fields.Datetime.context_timestamp(partners[0], fields.Datetime.now())
         m = self.CalendarEvent.create({
             'name': "mailTest1",
             'allday': False,
             'rrule': u'FREQ=DAILY;INTERVAL=1;COUNT=5',
             'recurrency': True,
             'partner_ids': partner_ids,
-            'start': fields.Datetime.to_string(now + timedelta(days=10)),
-            'stop': fields.Datetime.to_string(now + timedelta(days=15)),
+            'start': "2023-10-29 08:00:00",
+            'stop': "2023-11-03 08:00:00",
             })
 
         # every partner should have 1 mail sent
@@ -351,8 +350,8 @@ def _test_one_mail_per_attendee(self, partners):
             'allday': False,
             'recurrency': False,
             'partner_ids': partner_ids,
-            'start': fields.Datetime.to_string(now - timedelta(days=10)),
-            'stop': fields.Datetime.to_string(now - timedelta(days=9)),
+            'start': "2023-10-09 08:00:00",
+            'stop': "2023-10-10 08:00:00",
         })
 
         # no more email should be sent