Removing relation child while updating nullable fk as None

ormar/models/descriptors/descriptors.py

@@ -117,6 +117,8 @@ def __set__(self, instance: "Model", value: Any) -> None:
         else:
             # foreign key relation
             instance.__dict__[self.name] = model
+            if value is None and instance.Meta.model_fields[self.name].nullable:
+                instance._orm.remove(self.name, getattr(instance, self.name))
             instance.set_save_status(False)
 
 

tests/test_relations/test_foreign_keys.py

@@ -440,3 +440,15 @@ async def test_bulk_update_model_with_children():
                 is_best_seller=True
             ).all()
             assert len(best_seller_albums_db) == 2
+
+
+@pytest.mark.asyncio
+async def test_fk_update_to_none():
+    async with database:
+        async with database.transaction(force_rollback=True):
+            fantasies = await Album.objects.create(name="Limitless")
+            track = await Track.objects.create(album=fantasies, title="Test1", position=1)
+            assert track.album.name == "Limitless"
+            track.album = None
+            updated_track = await track.update(_columns=["album"])
+            assert updated_track.album is None