Fix sparse indexes when deleting

drf_kit/signals.py

@@ -1,6 +1,7 @@
 import logging
 
-from django.dispatch import Signal
+from django.db.models.signals import post_delete
+from django.dispatch import Signal, receiver
 
 logger = logging.getLogger(__name__)
 
@@ -40,3 +41,15 @@ def __exit__(self, *args, **kwargs):
 post_soft_delete = Signal(providing_args=["instance"])
 pre_undelete = Signal(providing_args=["instance"])
 post_undelete = Signal(providing_args=["instance"])
+
+
+@receiver(post_delete)
+def reorder_group(sender, instance, **kwargs):
+    from drf_kit.models import OrderedModelMixin  # pylint: disable=import-outside-toplevel
+
+    if not issubclass(sender, OrderedModelMixin):
+        return
+
+    if previous := instance.previous():
+        # trigger the reordering
+        previous.save()

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "drf-kit"
-version = "1.9.0"
+version = "1.10.0"
 description = "DRF Toolkit"
 authors = ["eduK <[email protected]>"]
 packages = [

test_app/tests/tests_model.py

@@ -458,3 +458,37 @@ def test_create_before_range(self):
         self.assertOrder(placement_2, 2)
         self.assertOrder(placement_3, 3)
         self.assertOrder(placement_4, 0)
+
+    def test_delete_within_range(self):
+        year = 1900
+
+        placement_1 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[0], prize="rock")
+        placement_2 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[1], prize="stone")
+        placement_3 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[2], prize="wand")
+        placement_4 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[3], prize="hug")
+
+        placement_2.delete()
+
+        for placement in [placement_1, placement_3, placement_4]:
+            placement.refresh_from_db()
+
+        self.assertOrder(placement_1, 0)
+        self.assertOrder(placement_3, 1)
+        self.assertOrder(placement_4, 2)
+
+    def test_delete_from_queryset(self):
+        year = 1900
+
+        placement_1 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[0], prize="rock")
+        placement_2 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[1], prize="stone")
+        placement_3 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[2], prize="wand")
+        placement_4 = TriWizardPlacement.objects.create(year=year, wizard=self.wizards[3], prize="hug")
+
+        TriWizardPlacement.objects.filter(id=placement_2.id).delete()
+
+        for placement in [placement_1, placement_3, placement_4]:
+            placement.refresh_from_db()
+
+        self.assertOrder(placement_1, 0)
+        self.assertOrder(placement_3, 1)
+        self.assertOrder(placement_4, 2)