From 5eab41f6177283fd377e33f3f411baaf2f406580 Mon Sep 17 00:00:00 2001
From: Guilherme Martins Crocetti
 <24530683+gmcrocetti@users.noreply.github.com>
Date: Thu, 21 Mar 2024 20:05:05 -0300
Subject: [PATCH] feat(monitor): Change default to None when the field is
 marked as nullable and no default is provided

---
 CHANGES.rst                             |  2 ++
 model_utils/fields.py                   | 14 ++------------
 tests/models.py                         |  1 +
 tests/test_fields/test_monitor_field.py | 20 +++++++++-----------
 4 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index e5e48e59..3cfeccc2 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -3,6 +3,8 @@ Changelog
 
 To be released
 --------------
+- Remove MonitorField deprecation warning. `None` - instead of
+  `django.utils.timezone.now` will be used when nullable and no default provided (GH-#599)
 - Add deprecation warning for MonitorField. The default value will be `None`
   instead of `django.utils.timezone.now` - when nullable and without a default.
 - Add Brazilian Portuguese translation (GH-#578)
diff --git a/model_utils/fields.py b/model_utils/fields.py
index e04ada2b..2fdd0b5e 100644
--- a/model_utils/fields.py
+++ b/model_utils/fields.py
@@ -1,6 +1,5 @@
 import secrets
 import uuid
-import warnings
 from collections.abc import Callable
 
 from django.conf import settings
@@ -108,17 +107,8 @@ class MonitorField(models.DateTimeField):
     """
 
     def __init__(self, *args, **kwargs):
-        if kwargs.get("null") and kwargs.get("default") is None:
-            warning_message = (
-                "{}.default is set to 'django.utils.timezone.now' - when nullable"
-                " and no default. This behavior will be deprecated in the next"
-                " major release in favor of 'None'. See"
-                " https://django-model-utils.readthedocs.io/en/stable/fields.html"
-                "#monitorfield for more information."
-            ).format(self.__class__.__name__)
-            warnings.warn(warning_message, DeprecationWarning)
-
-        kwargs.setdefault('default', now)
+        default = None if kwargs.get("null") else now
+        kwargs.setdefault('default', default)
         monitor = kwargs.pop('monitor', None)
         if not monitor:
             raise TypeError(
diff --git a/tests/models.py b/tests/models.py
index 6a5849e6..158bab7b 100644
--- a/tests/models.py
+++ b/tests/models.py
@@ -98,6 +98,7 @@ class TimeFrameManagerAdded(TimeFramedModel):
 class Monitored(models.Model):
     name = models.CharField(max_length=25)
     name_changed = MonitorField(monitor="name")
+    name_changed_nullable = MonitorField(monitor="name", null=True)
 
 
 class MonitorWhen(models.Model):
diff --git a/tests/test_fields/test_monitor_field.py b/tests/test_fields/test_monitor_field.py
index 8c53571d..f0041368 100644
--- a/tests/test_fields/test_monitor_field.py
+++ b/tests/test_fields/test_monitor_field.py
@@ -34,17 +34,15 @@ def test_no_monitor_arg(self):
         with self.assertRaises(TypeError):
             MonitorField()
 
-    def test_nullable_without_default_deprecation(self):
-        warning_message = (
-            "{}.default is set to 'django.utils.timezone.now' - when nullable"
-            " and no default. This behavior will be deprecated in the next"
-            " major release in favor of 'None'. See"
-            " https://django-model-utils.readthedocs.io/en/stable/fields.html"
-            "#monitorfield for more information."
-        ).format(MonitorField.__name__)
-
-        with self.assertWarns(DeprecationWarning, msg=warning_message):
-            MonitorField(monitor="foo", null=True, default=None)
+    def test_monitor_default_is_none_when_nullable(self):
+        self.assertIsNone(self.instance.name_changed_nullable)
+        expected_datetime = datetime(2022, 1, 18, 12, 0, 0, tzinfo=timezone.utc)
+
+        self.instance.name = "Jose"
+        with time_machine.travel(expected_datetime, tick=False):
+            self.instance.save()
+
+        self.assertEqual(self.instance.name_changed_nullable, expected_datetime)
 
 
 class MonitorWhenFieldTests(TestCase):