When a background job is scheduled without an instance, delete() on the job model will throw exceptions

[DanSheps]

Deployment Type

Self-hosted

NetBox Version

v4.1.2

Python Version

3.12

Steps to Reproduce

1. Create a JobRunner class
2. Do not assign an object to the job instance
3. Add the JobRunner.enqueue_once to the ready() of a plugin

Expected Behavior

NetBox will function normally

Observed Behavior

AttributeError is raised in Job.delete()

[alehaa]

I believe this is because delete() doesn't check if object_type is None.

rq_queue_name = get_config().QUEUE_MAPPINGS.get(self.object_type.model, RQ_QUEUE_DEFAULT)

In enqueue() this is handled by:

rq_queue_name = get_queue_for_model(object_type.model if object_type else None)

I suggest using the same lookup in both instances and add to add a test checking jobs actually can be deleted. If this is accepted, I volunteer for a PR.

[DanSheps]

Yup, I knew the problem, but thanks for pointing out the get_queue_for_model method.

[alehaa]

It seems that deleting jobs is already covered by a test case (test_enqueue_once_twice_different_schedule_at internally triggers a job.delete()). However, this only applies to jobs with an instance set. I'll add tests for jobs without instances during implementation of #16971, so this will be covered as well.