Support message log without message data

docs/usage.rst

@@ -264,6 +264,13 @@ that the message will be retried indefinitely. If you set this to a value of ``0
 the message will not be retried at all, any number greater than ``0`` will be the
 maximum number of retries (excluding the initial attempt).
 
+To not log the email contents after sending it, you can set ``MAILER_EMAIL_LOG_MESSAGE_DATA``
+to `False`. The default is ``True``, which means that the message will be stored with the full
+email content. If you set this to the value ``False``, only the message meta data and result
+status will be stored in the ``MessageLog`` table.
+Disabling storing the email content can be useful for privacy or performance reasons,
+it also helps to not increase the database size.
+
 Using the DontSendEntry table
 =============================
 

src/mailer/admin.py

@@ -6,12 +6,27 @@
 
 
 def show_to(message):
-    return ", ".join(message.to_addresses)
+    to_addresses = message.to_addresses
+    if to_addresses:
+        return ", ".join(message.to_addresses)
+    else:
+        return "<Message logging disabled>"
 
 
 show_to.short_description = "To"  # noqa: E305
 
 
+def show_subject(message):
+    subject = message.subject
+    if subject:
+        return subject
+    else:
+        return "<Message logging disabled>"
+
+
+show_subject.short_description = "Subject"  # noqa: E305
+
+
 class MessageAdminMixin:
     def plain_text_body(self, instance):
         email = instance.email
@@ -40,7 +55,7 @@ class DontSendEntryAdmin(admin.ModelAdmin):
 
 class MessageLogAdmin(MessageAdminMixin, admin.ModelAdmin):
 
-    list_display = ["id", show_to, "subject", "message_id", "when_attempted", "result"]
+    list_display = ["id", show_to, show_subject, "message_id", "when_attempted", "result"]
     list_filter = ["result"]
     date_hierarchy = "when_attempted"
     readonly_fields = ["plain_text_body", "message_id"]

src/mailer/migrations/0007_alter_messagelog_message_data.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.0.4 on 2024-04-13 09:37
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("mailer", "0006_message_retry_count"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="messagelog",
+            name="message_data",
+            field=models.TextField(null=True),
+        ),
+    ]

src/mailer/models.py

@@ -244,8 +244,11 @@ def log(self, message, result_code, log_message=""):
         create a log entry for an attempt to send the given message and
         record the given result and (optionally) a log message
         """
+        log_message_data = getattr(settings, "MAILER_EMAIL_LOG_MESSAGE_DATA", True)
+        message_data = message.message_data if log_message_data else None
+
         return self.create(
-            message_data=message.message_data,
+            message_data=message_data,
             message_id=get_message_id(message.email),
             when_added=message.when_added,
             priority=message.priority,
@@ -271,7 +274,7 @@ class MessageLog(BigAutoModel):
     """
 
     # fields from Message
-    message_data = models.TextField()
+    message_data = models.TextField(null=True)
     message_id = models.TextField(editable=False, null=True)
     when_added = models.DateTimeField(db_index=True)
     priority = models.PositiveSmallIntegerField(choices=PRIORITIES, db_index=True)
@@ -290,7 +293,10 @@ class Meta:
     def __str__(self):
         try:
             email = self.email
-            return f"On {self.when_attempted}, \"{email.subject}\" to {', '.join(email.to)}"
+            if email:
+                return f"On {self.when_attempted}, \"{email.subject}\" to {', '.join(email.to)}"
+            else:
+                return f'On {self.when_attempted}, "{self.message_id}"'
         except Exception:
             return "<MessageLog repr unavailable>"
 

tests/test_mailer.py

@@ -1,7 +1,7 @@
 import datetime
 import pickle
 import time
-from unittest.mock import Mock, patch
+from unittest.mock import Mock, PropertyMock, patch
 
 import django
 import lockfile
@@ -637,6 +637,32 @@ def test_message_log(self):
             self.assertEqual(log.to_addresses, [])
             self.assertEqual(log.subject, "")
 
+    def test_message_log_without_log_message_data(self):
+        with self.settings(
+            MAILER_EMAIL_BACKEND="django.core.mail.backends.locmem.EmailBackend",
+            MAILER_EMAIL_LOG_MESSAGE_DATA=False,
+        ):  # noqa
+            mailer.send_mail("Subject Log", "Body", "log1@example.com", ["1gol@example.com"])
+
+            self.assertEqual(Message.objects.count(), 1)
+            self.assertEqual(Message.objects.deferred().count(), 0)
+            self.assertEqual(MessageLog.objects.count(), 0)
+            when_added = Message.objects.first().when_added
+
+            engine.send_all()
+
+            self.assertEqual(Message.objects.count(), 0)
+            self.assertEqual(Message.objects.deferred().count(), 0)
+            self.assertEqual(MessageLog.objects.count(), 1)
+
+            log = MessageLog.objects.all()[0]
+
+            self.assertEqual(log.email, None)
+            self.assertEqual(log.message_data, None)
+            self.assertEqual(log.to_addresses, [])
+            self.assertEqual(log.subject, "")
+            self.assertEqual(log.when_added, when_added)
+
     def test_message_str(self):
         with self.settings(MAILER_EMAIL_BACKEND="django.core.mail.backends.locmem.EmailBackend"):
             mailer.send_mail("Subject Msg 中", "Body 中", "msg1@example.com", ["rec1@example.com"])
@@ -664,8 +690,12 @@ def test_message_log_str(self):
                 f'On {log.when_attempted}, "Subject Log 中" to 1gol@example.com',
             )
 
+            with patch.object(MessageLog, "when_attempted", new_callable=PropertyMock) as log_mock:
+                log_mock.side_effect = ValueError
+                self.assertEqual(str(log), "<MessageLog repr unavailable>")
+
             log.message_data = None
-            self.assertEqual(str(log), "<MessageLog repr unavailable>")
+            self.assertEqual(str(log), f'On {log.when_attempted}, "{log.message_id}"')
 
 
 class DbToEmailTest(TestCase):