[FIX] mail_post_defer: recover "view $model" button

Fixes a regression in https://github.com/OCA/social/pull/1380 that made posted messages lose the "View $model" button, even if the recipient had access.

@moduon MT-6348

mail_post_defer/models/mail_message_schedule.py

@@ -19,7 +19,7 @@ class MailMessageSchedule(models.Model):
         result = super()._group_by_model()
         for model, records in result.copy().items():
             # Move records without mail.thread mixin to a False key
-            if model and not hasattr(model, "_notify_thread"):
+            if model and not hasattr(self.env.get(model), "_notify_thread"):
                 result.pop(model)
                 result.setdefault(False, self.browse())
                 result[False] += records

mail_post_defer/tests/test_mail.py

@@ -2,6 +2,7 @@
 # License LGPL-3.0 or later (https://www.gnu.org/licenses/lgpl).
 
 import freezegun
+from lxml import html
 
 from odoo.exceptions import UserError
 from odoo.tests import tagged
@@ -216,6 +217,49 @@ class MessagePostCase(MailPostDeferCommon):
         self.assertFalse(hasattr(self.env["res.country"], "_notify_thread"))
         self.assertTrue(hasattr(self.env["res.partner"], "_notify_thread"))
 
+    def test_button_access(self):
+        """A button is added to the email to access the record."""
+        customer = self.env["res.partner"].create(
+            {"name": "Customer", "email": "customer@example.com"}
+        )
+        with self.mock_mail_gateway():
+            customer.message_post(
+                body="test body",
+                subject="test subject",
+                message_type="comment",
+                partner_ids=(self.partner_employee | customer).ids,
+            )
+            self.assertNoMail(self.partner_employee | customer)
+            # After a minute, mails are sent
+            with freezegun.freeze_time("2023-01-02 10:01:00"):
+                self.env["mail.message.schedule"]._send_notifications_cron()
+                self.env["mail.mail"].process_email_queue()
+                # Employee has a button that grants them access
+                customer_link = customer._notify_get_action_link("view")
+                employee_mail = self.assertSentEmail(
+                    self.env.user.partner_id,
+                    self.partner_employee,
+                    body_content="test body",
+                )
+                self.assertEqual(
+                    html.fromstring(employee_mail["body"])
+                    .xpath(f"//a[contains(@href, '{customer_link}')]")[0]
+                    .text_content()
+                    .strip(),
+                    "View Contact",
+                )
+                # Customer got the mail, but doesn't have access
+                customer_mail = self.assertSentEmail(
+                    self.env.user.partner_id,
+                    customer,
+                    body_content="test body",
+                )
+                self.assertFalse(
+                    html.fromstring(customer_mail["body"]).xpath(
+                        f"//a[contains(@href, '{customer_link}')]"
+                    )
+                )
+
 
 @tagged("-at_install", "post_install")
 @freezegun.freeze_time("2023-01-02 10:00:00")