Add status_changed field to upload_fields parameter during save if status field is present (#441)

* implementation/tests

* naming problem

AUTHORS.rst

@@ -15,6 +15,7 @@
 | Bo Marchman <bo.marchman@gmail.com>
 | Bojan Mihelac <bmihelac@mihelac.org>
 | Bruno Alla <bruno.alla@founders4schools.org.uk>
+| Bugra Aydin <bugraaydin.cs@gmail.com>
 | Craig Anderson <craiga@craiga.id.au>
 | Daniel Andrlik <daniel@andrlik.org>
 | Daniel Stanton <stringsonfire@me.com>

CHANGES.rst

@@ -13,6 +13,9 @@ CHANGES
 - Add available_objects manager to SoftDeletableModel and add deprecation
   warning to objects manager.
 - Add support for `Django 3.1`
+- StatusModel now automatically adds 'status_changed' field during save as an
+  update_fieldsparameter when 'status' is present in it to make sure it is not
+  forgotten.
 
 4.0.0 (2019-12-11)
 ------------------

model_utils/models.py

@@ -67,6 +67,20 @@ class StatusModel(models.Model):
     status = StatusField(_('status'))
     status_changed = MonitorField(_('status changed'), monitor='status')
 
+    def save(self, *args, **kwargs):
+        """
+        Overriding the save method in order to make sure that
+        status_changed field is updated even if it is not given as
+        a parameter to the update field argument.
+        """
+        if (
+            'update_fields' in kwargs
+            and 'status' in kwargs['update_fields']
+            and 'status_changed' not in kwargs['update_fields']
+        ):
+            kwargs['update_fields'] += ['status_changed']
+        super().save(*args, **kwargs)
+
     class Meta:
         abstract = True
 

tests/test_models/test_status_model.py

@@ -38,6 +38,36 @@ class StatusModelTests(TestCase):
         t1.save()
         self.assertTrue(t1.status_changed > date_active_again)
 
+    def test_save_with_update_fields_overrides_status_changed_provided(self):
+        '''
+        Tests if the save method updated status_changed field
+        accordingly when update_fields is used as an argument
+        and status_changed is provided
+        '''
+        with freeze_time(datetime(2020,1,1)):
+            t1 = Status.objects.create()
+        
+        with freeze_time(datetime(2020,1,2)):
+            t1.status = Status.on_hold
+            t1.save(update_fields=['status', 'status_changed'])
+        
+        self.assertEqual(t1.status_changed, datetime(2020,1,2))
+        
+    def test_save_with_update_fields_overrides_status_changed_not_provided(self):
+        '''
+        Tests if the save method updated status_changed field
+        accordingly when update_fields is used as an argument
+        with status and status_changed is not provided
+        '''
+        with freeze_time(datetime(2020,1,1)):
+            t1 = Status.objects.create()
+            
+        with freeze_time(datetime(2020,1,2)):
+            t1.status = Status.on_hold
+            t1.save(update_fields=['status'])
+            
+        self.assertEqual(t1.status_changed, datetime(2020,1,2))
+
 
 class StatusModelPlainTupleTests(StatusModelTests):
     def setUp(self):