Fixes #9952: Prevent InvalidMove when attempting to assign a nested child object as parent

docs/release-notes/version-3.2.md

@@ -23,6 +23,7 @@
 * [#9919](https://github.com/netbox-community/netbox/issues/9919) - Fix potential XSS avenue via linked objects in tables
 * [#9948](https://github.com/netbox-community/netbox/issues/9948) - Fix TypeError exception when requesting API tokens list as non-authenticated user
 * [#9949](https://github.com/netbox-community/netbox/issues/9949) - Fix KeyError exception resulting from invalid API token provisioning request
+* [#9952](https://github.com/netbox-community/netbox/issues/9952) - Prevent InvalidMove when attempting to assign a nested child object as parent
 
 ---
 

netbox/netbox/models/__init__.py

@@ -89,9 +89,9 @@ class NestedGroupModel(NetBoxFeatureSet, MPTTModel):
         super().clean()
 
         # An MPTT model cannot be its own parent
-        if self.pk and self.parent_id == self.pk:
+        if self.pk and self.parent and self.parent in self.get_descendants(include_self=True):
             raise ValidationError({
-                "parent": "Cannot assign self as parent."
+                "parent": f"Cannot assign self or child {self._meta.verbose_name} as parent."
             })