Add pre and post clone save signals (#680)

* Add pre and post clone save signals

* Fix auto commit

* Fix assert annotations

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Tonye Jack <[email protected]>

model_clone/mixin.py

@@ -10,6 +10,7 @@
 from django.utils.text import slugify
 
 from model_clone.apps import ModelCloneConfig
+from model_clone.signals import post_clone_save, pre_clone_save
 from model_clone.utils import (
     clean_value,
     context_mutable_attribute,
@@ -233,13 +234,16 @@ def make_clone(self, attrs=None, sub_clone=False, using=None, parent=None):
 
         duplicate = self.pre_save_duplicate(duplicate)
         duplicate = self.__duplicate_m2o_fields(duplicate, using=using)
+
+        pre_clone_save.send(sender=self.__class__, instance=duplicate)
+
         duplicate.save(using=using)
 
         duplicate = self.__duplicate_o2o_fields(duplicate, using=using)
         duplicate = self.__duplicate_o2m_fields(duplicate, using=using)
         duplicate = self.__duplicate_m2m_fields(duplicate, using=using)
 
-        duplicate.save(using=using)
+        post_clone_save.send(sender=self.__class__, instance=duplicate)
 
         return duplicate
 

model_clone/signals.py

@@ -0,0 +1,4 @@
+from django.db.models.signals import ModelSignal
+
+pre_clone_save = ModelSignal(use_caching=True)
+post_clone_save = ModelSignal(use_caching=True)

model_clone/tests/test_clone_signals.py

@@ -0,0 +1,38 @@
+from django.contrib.auth import get_user_model
+from django.test import TestCase
+from django.utils import timezone
+from django.utils.text import slugify
+
+from sample.models import Book, Edition
+
+User = get_user_model()
+
+
+class CloneSignalsTestCase(TestCase):
+    REPLICA_DB_ALIAS = "replica"
+    databases = {
+        "default",
+        "replica",
+    }
+
+    @classmethod
+    def setUpTestData(cls):
+        cls.user = User.objects.create(username="user")
+
+    def test_signals(self):
+        name = "New Book"
+        first_published_at = timezone.datetime(
+            1970, 1, 1, tzinfo=timezone.get_default_timezone()
+        )
+        book = Book.objects.create(
+            name=name,
+            created_by=self.user,
+            slug=slugify(name),
+            published_at=first_published_at,
+        )
+        self.assertEqual(book.published_at, first_published_at)
+        edition = Edition.objects.create(seq=1, book=book)
+        cloned_edition = edition.make_clone()
+        self.assertEqual(cloned_edition.seq, 2)
+        book.refresh_from_db()
+        self.assertNotEqual(book.published_at, first_published_at)

sample/__init__.py

@@ -0,0 +1 @@
+default_app_config = "sample.apps.SampleConfig"

sample/apps.py

@@ -1,6 +1,10 @@
+# pylint: disable=unused-import
 from django.apps import AppConfig
 
 
 class SampleConfig(AppConfig):
     default_auto_field = "django.db.models.BigAutoField"
     name = "sample"
+
+    def ready(self):
+        from . import signals  # noqa: F401

sample/signals.py

@@ -0,0 +1,18 @@
+from django.dispatch import receiver
+from django.utils import timezone
+
+from model_clone.signals import post_clone_save, pre_clone_save
+
+from .models import Edition
+
+
+@receiver(pre_clone_save, sender=Edition)
+def increase_seq(sender, instance, **kwargs):
+    instance.seq += 1
+
+
+@receiver(post_clone_save, sender=Edition)
+def update_book_published_at(sender, instance, **kwargs):
+    if instance.book:
+        instance.book.published_at = timezone.now()
+        instance.book.save(update_fields=["published_at"])