[REF] mail: use a datetime instead of a char for the mail scheduled date

Purpose
=======

Historically, we use a char field on the <mail.mail> to match the field type
on the <mail.template>. But even it's useful to have a char field on the mail
template (which can contains QWeb code or Jinja previously to Odoo 15.0) it is
not that useful for the <mail.mail> to keep this char type, because the value
is already rendered. Moreover this forces to have some code convert and store
datetime values using the standard format and in UTC.

We now correctly use a datetime field, as all other fields of that kind in
Odoo.

Task-2826699 (Mail: use datetime for scheduled_date mail field instead of char)
Prepares Task-2207626 (Rating: Delay rating notification to ease feedback)

Part-of: odoo/odoo#95623
Co-authored-by: Thibault Delavallée <tde@odoo.com>

addons/mail/models/mail_mail.py

@@ -85,7 +85,7 @@ class MailMail(models.Model):
         'Auto Delete',
         help="This option permanently removes any track of email after it's been sent, including from the Technical menu in the Settings, in order to preserve storage space of your Odoo database.")
     to_delete = fields.Boolean('To Delete', help='If set, the mail will be deleted during the next Email Queue CRON run.')
-    scheduled_date = fields.Char('Scheduled Send Date',
+    scheduled_date = fields.Datetime('Scheduled Send Date',
         help="If set, the queue manager will send the email after the date. If not set, the email will be send as soon as possible. Unless a timezone is specified, it is considered as being in UTC timezone.")
     fetchmail_server_id = fields.Many2one('fetchmail.server', "Inbound Mail Server", readonly=True)
 
@@ -132,10 +132,9 @@ class MailMail(models.Model):
                 values['is_notification'] = True
             if values.get('scheduled_date'):
                 parsed_datetime = self._parse_scheduled_datetime(values['scheduled_date'])
-                if parsed_datetime:
-                    values['scheduled_date'] = parsed_datetime.strftime(tools.DEFAULT_SERVER_DATETIME_FORMAT)
-                else:
-                    values['scheduled_date'] = False
+                values['scheduled_date'] = parsed_datetime.replace(tzinfo=None) if parsed_datetime else False
+            else:
+                values['scheduled_date'] = False  # void string crashes
         new_mails = super(MailMail, self).create(values_list)
 
         new_mails_w_attach = self
@@ -150,10 +149,7 @@ class MailMail(models.Model):
     def write(self, vals):
         if vals.get('scheduled_date'):
             parsed_datetime = self._parse_scheduled_datetime(vals['scheduled_date'])
-            if parsed_datetime:
-                vals['scheduled_date'] = parsed_datetime.strftime(tools.DEFAULT_SERVER_DATETIME_FORMAT)
-            else:
-                vals['scheduled_date'] = False
+            vals['scheduled_date'] = parsed_datetime.replace(tzinfo=None) if parsed_datetime else False
         res = super(MailMail, self).write(vals)
         if vals.get('attachment_ids'):
             for mail in self:

addons/mail/models/mail_template.py

@@ -4,7 +4,6 @@
 import base64
 import logging
 
-
 from odoo import _, api, fields, models, tools, Command
 from odoo.exceptions import UserError
 from odoo.tools import is_html_empty

addons/test_mail/tests/test_mail_mail.py

@@ -231,7 +231,7 @@ class TestMailMail(TestMailCommon):
             (now + timedelta(hours=-3)).strftime("%H:%M:%S %d-%m-%Y") + " -0400",
         ]
         expected_datetimes = [
-            False, '', False,
+            False, False, False,
             now, now - pytz.timezone('Australia/Brisbane').utcoffset(now),
             now - timedelta(days=1), now + timedelta(days=1), now + timedelta(days=1),
             now + timedelta(hours=-1),
@@ -253,9 +253,8 @@ class TestMailMail(TestMailCommon):
         ])
 
         for mail, expected_datetime, scheduled_datetime in zip(mails, expected_datetimes, scheduled_datetimes):
-            expected = expected_datetime.strftime(tools.DEFAULT_SERVER_DATETIME_FORMAT) if expected_datetime else expected_datetime
-            self.assertEqual(mail.scheduled_date, expected,
-                             'Scheduled date: %s should be stored as %s, received %s' % (scheduled_datetime, expected, mail.scheduled_date))
+            self.assertEqual(mail.scheduled_date, expected_datetime,
+                             'Scheduled date: %s should be stored as %s, received %s' % (scheduled_datetime, expected_datetime, mail.scheduled_date))
             self.assertEqual(mail.state, 'outgoing')
 
         with freeze_time(now):