Move change_tracking_fields from TrackingModelMixin to the registry

docs/development/application-registry.md

@@ -8,6 +8,10 @@ The registry can be inspected by importing `registry` from `extras.registry`.
 
 ## Stores
 
+### `counter_fields`
+
+A dictionary mapping of models to foreign keys with which cached counter fields are associated.
+
 ### `data_backends`
 
 A dictionary mapping data backend types to their respective classes. These are used to interact with [remote data sources](../models/core/datasource.md).

netbox/netbox/registry.py

@@ -21,6 +21,7 @@ class Registry(dict):
 
 # Initialize the global registry
 registry = Registry({
+    'counter_fields': collections.defaultdict(set),
     'data_backends': dict(),
     'denormalized_fields': collections.defaultdict(list),
     'model_features': dict(),

netbox/utilities/counter.py

@@ -1,10 +1,10 @@
 from django.apps import apps
 from django.db.models import F
-from django.db.models.signals import post_delete, post_save, pre_save
+from django.db.models.signals import post_delete, post_save
 from functools import partial
 
+from netbox.registry import registry
 from .fields import CounterCacheField
-from .mixins import TrackingModelMixin
 
 
 def post_save_receiver_counter(counter_instance, sender, instance, created, **kwargs):
@@ -42,9 +42,8 @@ class Counter:
         self.parent_model = self.foreign_key_field.related_model
 
         # add the field to be tracked for changes in case of update
-        field_name = f"{self.foreign_key_field.name}_id"
-        if hasattr(self.child_model, 'change_tracking_fields') and field_name not in self.child_model.change_tracking_fields:
-            self.child_model.change_tracking_fields.append(field_name)
+        change_tracking_fields = registry['counter_fields'][self.child_model]
+        change_tracking_fields.add(f"{self.foreign_key_field.name}_id")
 
         self.connect()
 

netbox/utilities/mixins.py

@@ -1,5 +1,7 @@
 from django.db.models.query_utils import DeferredAttribute
 
+from netbox.registry import registry
+
 
 class Tracker:
     def __init__(self, instance):
@@ -8,7 +10,6 @@ class Tracker:
 
 
 class TrackingModelMixin:
-    change_tracking_fields = []
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
@@ -21,10 +22,8 @@ class TrackingModelMixin:
         return self._state._tracker
 
     def save(self, *args, **kwargs):
-        if not self.change_tracking_fields:
-            return super().save(*args, **kwargs)
-
         super().save(*args, **kwargs)
+
         if self.tracker.changed:
             if update_fields := kwargs.get('update_fields', None):
                 for field in update_fields:
@@ -33,8 +32,9 @@ class TrackingModelMixin:
                 self.tracker.changed = {}
 
     def __setattr__(self, name, value):
-        if hasattr(self, "_initialized") and self.change_tracking_fields:
-            if name in self.tracker.instance.change_tracking_fields:
+        if hasattr(self, "_initialized"):
+            change_tracking_fields = registry['counter_fields'][self.__class__]
+            if name in change_tracking_fields:
                 if name not in self.tracker.changed:
                     if name in self.__dict__:
                         old_value = getattr(self, name)