Closes #15490: CustomValidator support for accessing related object attribute via dotted path

netbox/extras/validators.py

@@ -151,14 +151,14 @@ class CustomValidator:
             return []
 
         # Raise a ValidationError for unknown attributes
-        if not hasattr(instance, name):
+        try:
+            return operator.attrgetter(name)(instance)
+        except AttributeError:
             raise ValidationError(_('Invalid attribute "{name}" for {model}').format(
                 name=name,
                 model=instance.__class__.__name__
             ))
 
-        return getattr(instance, name)
-
     def get_validator(self, descriptor, value):
         """
         Instantiate and return the appropriate validator based on the descriptor given. For