From 348fca7e28c78df33996c8097b298881f9b7acc9 Mon Sep 17 00:00:00 2001
From: jeremystretch <jeremy@netverity.dev>
Date: Sun, 11 Apr 2021 12:57:53 -0400
Subject: [PATCH] Fixes #6117: Handle exception when attempting to assign an
 MPTT-enabled model as its own parent

---
 docs/release-notes/version-2.10.md |  1 +
 netbox/dcim/models/racks.py        |  6 ++++++
 netbox/dcim/models/sites.py        | 10 ++++++++++
 netbox/tenancy/models.py           | 10 ++++++++++
 4 files changed, 27 insertions(+)

diff --git a/docs/release-notes/version-2.10.md b/docs/release-notes/version-2.10.md
index 390c318f7..7d99959cc 100644
--- a/docs/release-notes/version-2.10.md
+++ b/docs/release-notes/version-2.10.md
@@ -17,6 +17,7 @@
 * [#6073](https://github.com/netbox-community/netbox/issues/6073) - Permit users to manage their own REST API tokens without needing explicit permission
 * [#6081](https://github.com/netbox-community/netbox/issues/6081) - Fix interface connections REST API endpoint
 * [#6108](https://github.com/netbox-community/netbox/issues/6108) - Do not infer tenant assignment from parent objects for prefixes, IP addresses
+* [#6117](https://github.com/netbox-community/netbox/issues/6117) - Handle exception when attempting to assign an MPTT-enabled model as its own parent
 * [#6131](https://github.com/netbox-community/netbox/issues/6131) - Correct handling of boolean fields when cloning objects
 
 ---
diff --git a/netbox/dcim/models/racks.py b/netbox/dcim/models/racks.py
index dfaf7da61..0bd7e5afd 100644
--- a/netbox/dcim/models/racks.py
+++ b/netbox/dcim/models/racks.py
@@ -111,6 +111,12 @@ class RackGroup(MPTTModel, ChangeLoggedModel):
     def clean(self):
         super().clean()
 
+        # An MPTT model cannot be its own parent
+        if self.pk and self.parent_id == self.pk:
+            raise ValidationError({
+                "parent": "Cannot assign self as parent."
+            })
+
         # Parent RackGroup (if any) must belong to the same Site
         if self.parent and self.parent.site != self.site:
             raise ValidationError(f"Parent rack group ({self.parent}) must belong to the same site ({self.site})")
diff --git a/netbox/dcim/models/sites.py b/netbox/dcim/models/sites.py
index 923b33124..908750905 100644
--- a/netbox/dcim/models/sites.py
+++ b/netbox/dcim/models/sites.py
@@ -7,6 +7,7 @@ from timezone_field import TimeZoneField
 
 from dcim.choices import *
 from dcim.constants import *
+from django.core.exceptions import ValidationError
 from dcim.fields import ASNField
 from extras.models import ChangeLoggedModel, CustomFieldModel, ObjectChange, TaggedItem
 from extras.utils import extras_features
@@ -87,6 +88,15 @@ class Region(MPTTModel, ChangeLoggedModel):
             object_data=serialize_object(self, exclude=['level', 'lft', 'rght', 'tree_id'])
         )
 
+    def clean(self):
+        super().clean()
+
+        # An MPTT model cannot be its own parent
+        if self.pk and self.parent_id == self.pk:
+            raise ValidationError({
+                "parent": "Cannot assign self as parent."
+            })
+
 
 #
 # Sites
diff --git a/netbox/tenancy/models.py b/netbox/tenancy/models.py
index 3ba644c09..dbb8c4835 100644
--- a/netbox/tenancy/models.py
+++ b/netbox/tenancy/models.py
@@ -1,3 +1,4 @@
+from django.core.exceptions import ValidationError
 from django.db import models
 from django.urls import reverse
 from mptt.models import MPTTModel, TreeForeignKey
@@ -74,6 +75,15 @@ class TenantGroup(MPTTModel, ChangeLoggedModel):
             object_data=serialize_object(self, exclude=['level', 'lft', 'rght', 'tree_id'])
         )
 
+    def clean(self):
+        super().clean()
+
+        # An MPTT model cannot be its own parent
+        if self.pk and self.parent_id == self.pk:
+            raise ValidationError({
+                "parent": "Cannot assign self as parent."
+            })
+
 
 @extras_features('custom_fields', 'custom_links', 'export_templates', 'webhooks')
 class Tenant(ChangeLoggedModel, CustomFieldModel):