Assigning assigned_object to None doesn't work unless it's referenced

[aj2s]

pynetbox version

v7.5.0

NetBox version

v4.3.7

Python version

3.12

Steps to Reproduce

mac_address = nb.dcim.mac_addresses.get(id=30180)
interface = mac_address.assigned_object

# Uncommenting this gets it working as expected
# print(interface.primary_mac_address)

interface.primary_mac_address = None
print(interface.save())

Expected Behavior

I expected the primary mac address to be unset

Observed Behavior

The primary mac address was still set.

[arthanson]

@aj2s This works fine for me, the primary Mac addresss was reset checked in both API and UI. Can you please double-check.

mac_address = nb.dcim.mac_addresses.get(id=1)
print(mac_address)
interface = mac_address.assigned_object
print(interface.primary_mac_address)
interface.primary_mac_address = None
interface.save()
mac_address = nb.dcim.mac_addresses.get(id=1)
interface = mac_address.assigned_object
print(interface.primary_mac_address)

[aj2s]

Thanks for the quick triage! That does work, but that's only because there's the call to print(interface.primary_mac_address) on line 4. It does not work for me when I *do not print / reference interface.primary_mac_address anywhere.

Is that expected? If so, it's not intuitive to me.

Here's an updated snippet with the line in question separated out for clarity

nb = pynetbox.api(os.environ["NETBOX_URL"], os.environ["NETBOX_TOKEN"])
mac_address = nb.dcim.mac_addresses.get(id=MAC_ADDRESS_ID)
interface = mac_address.assigned_object

# Commenting this out / not referencing interface.primary_mac_address causes this snippet to not update interface.primary_mac_address on interface.save()
print("primary mac before", interface.primary_mac_address)

interface.primary_mac_address = None
interface.save()
mac_address = nb.dcim.mac_addresses.get(id=MAC_ADDRESS_ID)
interface = mac_address.assigned_object
print("primary mac after", interface.primary_mac_address)

[aj2s]

I have confirmed the call to save() is not triggering any network request. From what I understand, that means that the call to _diff detects no change, right? I'm interested in deepening my understanding of how pynetbox works internally, but that will not be this week :)

Script:

import os
import pynetbox
import logging

MAC_ADDRESS_ID = 30180

logger = logging.getLogger(__name__)
logging.basicConfig(level=logging.DEBUG, format="%(levelname)s: %(message)s")
nb = pynetbox.api(os.environ["NETBOX_URL"], os.environ["NETBOX_TOKEN"])

mac_address = nb.dcim.mac_addresses.get(id=MAC_ADDRESS_ID)
interface = mac_address.assigned_object

logging.info("Setting primary_mac_address to None")
interface.primary_mac_address = None

logging.info("Saving")
interface.save()
logging.info("Supposedly saved")

mac_address = nb.dcim.mac_addresses.get(id=MAC_ADDRESS_ID)
interface = mac_address.assigned_object
logging.info("primary mac after: %s", interface.primary_mac_address)

Output (with redacted domain):

DEBUG: Starting new HTTPS connection (1): netbox.example.com:443
DEBUG: https://netbox.example.com:443 "GET /api/dcim/mac-addresses/?id=30180&limit=0 HTTP/1.1" 200 923
INFO: Setting primary_mac_address to None
INFO: Saving
INFO: Supposedly saved
DEBUG: https://netbox.example.com:443 "GET /api/dcim/mac-addresses/?id=30180&limit=0 HTTP/1.1" 200 923
DEBUG: https://netbox.example.com:443 "GET /api/dcim/interfaces/24648/ HTTP/1.1" 200 797
DEBUG: https://netbox.example.com:443 "GET /api/dcim/mac-addresses/30180/ HTTP/1.1" 200 871
INFO: primary mac after: 8C:1F:64:05:5D:BF

[arthanson]

Does look like the print is causing it to be de-reffed and makes it work. Adding to backlog for more investigation as it does not seem correct.