Remove all paths on element deletion

arkindex/documents/apps.py

@@ -3,3 +3,6 @@ from django.apps import AppConfig
 
 class ElementsConfig(AppConfig):
     name = 'documents'
+
+    def ready(self):
+        from arkindex.documents import signals  # noqa

arkindex/documents/models.py

@@ -82,7 +82,7 @@ class ElementPath(models.Model):
     An element can have multiple paths up to the top
     """
     id = models.UUIDField(default=uuid.uuid4, primary_key=True)
-    element = models.ForeignKey('documents.Element', related_name='paths', on_delete=models.DO_NOTHING)
+    element = models.ForeignKey('documents.Element', related_name='paths', on_delete=models.CASCADE)
     path = ArrayField(
         models.UUIDField(),
     )

arkindex/documents/signals.py

+from django.db.models.signals import pre_delete
+from django.dispatch import receiver
+from arkindex.documents.models import Element, ElementPath
+
+
+@receiver(pre_delete, sender=Element)
+def pre_delete_handler(sender, instance, *args, **kwargs):
+    assert isinstance(instance, Element)
+    # Run remove_child on all direct parents of the element
+    for parent in ElementPath.objects.filter(path__last=instance.id):
+        parent.remove_child(instance)