From 619728a0489b5418415451befe0fbad96852187e Mon Sep 17 00:00:00 2001
From: Jeremy Stretch <jstretch@netboxlabs.com>
Date: Mon, 1 Dec 2025 13:35:14 -0500
Subject: [PATCH] Ensure cable paths are retraced when port mappings are
 changes via form

---
 netbox/dcim/forms/mixins.py  | 12 ++++++++++++
 netbox/dcim/models/cables.py |  2 +-
 netbox/dcim/signals.py       | 26 +++++++++++++-------------
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/netbox/dcim/forms/mixins.py b/netbox/dcim/forms/mixins.py
index 91a0501dd..b2fc46bc3 100644
--- a/netbox/dcim/forms/mixins.py
+++ b/netbox/dcim/forms/mixins.py
@@ -1,6 +1,8 @@
 from django import forms
 from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import ObjectDoesNotExist, ValidationError
+from django.db import connection
+from django.db.models.signals import post_save
 from django.utils.translation import gettext_lazy as _
 
 from dcim.constants import LOCATION_SCOPE_TYPES
@@ -191,3 +193,13 @@ class FrontPortFormMixin(forms.Form):
                 })
             )
         self.port_mapping_model.objects.bulk_create(mappings)
+        # Send post_save signals
+        for mapping in mappings:
+            post_save.send(
+                sender=PortMapping,
+                instance=mapping,
+                created=True,
+                raw=False,
+                using=connection,
+                update_fields=None
+            )
diff --git a/netbox/dcim/models/cables.py b/netbox/dcim/models/cables.py
index 9d8c2c290..e75b4c110 100644
--- a/netbox/dcim/models/cables.py
+++ b/netbox/dcim/models/cables.py
@@ -31,7 +31,7 @@ __all__ = (
     'CableTermination',
 )
 
-logger = logging.getLogger(__name__)
+logger = logging.getLogger(f'netbox.{__name__}')
 
 trace_paths = Signal()
 
diff --git a/netbox/dcim/signals.py b/netbox/dcim/signals.py
index 81cb0ae6c..5ec1f68d7 100644
--- a/netbox/dcim/signals.py
+++ b/netbox/dcim/signals.py
@@ -1,5 +1,6 @@
 import logging
 
+from django.db.models import Q
 from django.db.models.signals import post_save, post_delete
 from django.dispatch import receiver
 
@@ -7,7 +8,7 @@ from dcim.choices import CableEndChoices, LinkStatusChoices
 from virtualization.models import VMInterface
 from .models import (
     Cable, CablePath, CableTermination, ConsolePort, ConsoleServerPort, Device, DeviceBay, FrontPort, Interface,
-    InventoryItem, ModuleBay, PathEndpoint, PowerOutlet, PowerPanel, PowerPort, Rack, RearPort, Location,
+    InventoryItem, ModuleBay, PathEndpoint, PortMapping, PowerOutlet, PowerPanel, PowerPort, Rack, RearPort, Location,
     VirtualChassis,
 )
 from .models.cables import trace_paths
@@ -135,6 +136,17 @@ def retrace_cable_paths(instance, **kwargs):
         cablepath.retrace()
 
 
+@receiver((post_delete, post_save), sender=PortMapping)
+def update_passthrough_port_paths(instance, **kwargs):
+    """
+    When a PortMapping is created or deleted, retrace any CablePaths which traverse its front and/or rear ports.
+    """
+    for cablepath in CablePath.objects.filter(
+        Q(_nodes__contains=instance.front_port) | Q(_nodes__contains=instance.rear_port)
+    ):
+        cablepath.retrace()
+
+
 @receiver(post_delete, sender=CableTermination)
 def nullify_connected_endpoints(instance, **kwargs):
     """
@@ -150,18 +162,6 @@ def nullify_connected_endpoints(instance, **kwargs):
         cablepath.retrace()
 
 
-# TODO: Adapt signal handler to act on changes to port mappings
-@receiver(post_save, sender=FrontPort)
-def extend_rearport_cable_paths(instance, created, raw, **kwargs):
-    """
-    When a new FrontPort is created, add it to any CablePaths which end at its corresponding RearPort.
-    """
-    if created and not raw:
-        for mapping in instance.mappings.prefetch_related('rear_port'):
-            for cablepath in CablePath.objects.filter(_nodes__contains=mapping.rear_port):
-                cablepath.retrace()
-
-
 @receiver(post_save, sender=Interface)
 @receiver(post_save, sender=VMInterface)
 def update_mac_address_interface(instance, created, raw, **kwargs):