Unable to revert a branch that removed a device.

[ewscott9]

Plugin Version

0.5.0

NetBox Version

NetBox Community v4.1.0 (2024-09-03) (In Netbox-Docker-3.0.1)

Python Version

3.12.3

Steps to Reproduce

On main branch:

Create Device Role "test":
name,slug,color
"test","test",888888

Create Manufacturer "test":
name,slug
"test","test"

Create Device Type "test":
manufacturer,model,slug,u_height
"test","test","test",1.0

Create Site "test":
name,slug,status
"test","test",active

Create Device "test" and "test2":
role,manufacturer,device_type,status,site,name
"test","test","test",active,"test","test"
"test","test","test",active,"test","test2"

Create Interfaces on the 2 test devices:
device,name,type
test,1,1000base-tx
test2,1,1000base-tx

Create Cable:
side_a_device,side_a_type,side_a_name,side_b_device,side_b_type,side_b_name,label
test,dcim.interface,1,test2,dcim.interface,1,"test:1,test2:1"

Create branch "test":
name: test

On Branch "test":

Activate branch "test"
Delete "test" device
Revert "test" branch

Expected Behavior

The branch should revert.

Observed Behavior

It fails when I try to revert the branch.
I get the following log for the revert branch job:

{
    "log": [
        "Reverting branch test (branch_zwiumn32)",
        "Found 3 changes to revert",
        "Setting branch status to reverting",
        "Undoing change DCIM | device test deleted by ewscott using default",
        "Restoring device <DeserializedObject: dcim.Device(pk=16)>",
        "Undoing change DCIM | cable termination Cable test:1,test2:1 to 1 deleted by ewscott using default",
        "Restoring cable termination <DeserializedObject: dcim.CableTermination(pk=23)>",
        "'NoneType' object has no attribute 'type'"
    ]
}

Seems like it's failing to recreate a cable connection

[ewscott9]

I tested, and I don't seem to have a problem removing a single cable termination, and reverting it. I'll have to run more testing, but seems to be an issue with reverting after merging a branch that deleted a device.

[jeremystretch]

@ewscott9 please modify your post above to include exact reproduction steps, beginning with the creation of any objects to be deleted.

[ewscott9]

Thanks @jeremystretch I updated the reproduction steps.

I did some additional testing, and it will revert a device delete unless there is a cable connection between 2 devices.

[ewscott9]

I'm also getting an error when trying to merge a branch after I create a device that has an interface. I get a DeserializationError("['Invalid WWN format: ']: (dcim.interface:pk=180) field_value was ''") error. Might be related.

[jeremystretch]

The root issue here appears to be the generic foreign key termination on NetBox's CableTermination model. Although the termination_type and termination_id fields are populated for the object when reverting the branch, the GFK itself is not:

Traceback (most recent call last):
  File "/home/jstretch/projects/nbl-netbox-branching/netbox_branching/models/branches.py", line 412, in revert
    change.undo(logger=logger)
  File "/home/jstretch/projects/nbl-netbox-branching/netbox_branching/models/changes.py", line 91, in undo
    instance.object.full_clean()
  File "/home/jstretch/projects/netbox/venv/lib/python3.10/site-packages/django/db/models/base.py", line 1536, in full_clean
    self.clean()
  File "/home/jstretch/projects/netbox/netbox/dcim/models/cables.py", line 341, in clean
    if self.termination_type.model == 'interface' and self.termination.type in NONCONNECTABLE_IFACE_TYPES:
AttributeError: 'NoneType' object has no attribute 'type'

The best approach here is probably to ensure any GFKs are populated on each object during deserialization, much as a form or API serializer would.

[ewscott9]

The best approach here is probably to ensure any GFKs are populated on each object during deserialization, much as a form or API serializer would.

How would I go about doing that?

[jeremystretch]

@ewscott9 sorry, that was a note on a potential solution for the bug, not something that you can do as a user.

[ewscott9]

No problem. Thanks for looking into the issue.

[arthanson]

Another issue here is that the objects are serialized in the wrong order:

<class 'dcim.models.devices.Device'>
<class 'dcim.models.cables.CableTermination'>
<class 'dcim.models.device_components.Interface'>

The interface needs to be deserialized after the CableTermination