Allowed assigning an IP address to either a device or a VM

netbox/dcim/models.py

@@ -1241,6 +1241,10 @@ class Interface(models.Model):
                 )
             })
 
+    @property
+    def parent(self):
+        return self.device or self.virtual_machine
+
     @property
     def is_virtual(self):
         return self.form_factor in VIRTUAL_IFACE_TYPES