AttributeError when running database-changing Job from nautobot-server runjob --commit

[glennmatthews]

Environment

• Python version:
• Nautobot version: 1.1.3

Steps to Reproduce

1. Use the nautobot-server runjob --commit <job> command to enqueue a Job that will make any change to the database when run
2. When the Job calls any model's save() method, an AttributeError is thrown:

File "/usr/local/lib/python3.7/site-packages/django/db/models/base.py", line 754, in save
    force_update=force_update, update_fields=update_fields)
  File "/usr/local/lib/python3.7/site-packages/django/db/models/base.py", line 803, in save_base
    update_fields=update_fields, raw=raw, using=using,
  File "/usr/local/lib/python3.7/site-packages/django/dispatch/dispatcher.py", line 179, in send
    for receiver in self._live_receivers(sender)
  File "/usr/local/lib/python3.7/site-packages/django/dispatch/dispatcher.py", line 179, in 
    for receiver in self._live_receivers(sender)
  File "/usr/local/lib/python3.7/site-packages/nautobot/utilities/utils.py", line 311, in _curried
    return _curried_func(*args, *moreargs, **{**kwargs, **morekwargs})
  File "/usr/local/lib/python3.7/site-packages/nautobot/extras/signals.py", line 62, in _handle_changed_object
    objectchange.user = _get_user_if_authenticated(request, objectchange)
  File "/usr/local/lib/python3.7/site-packages/nautobot/extras/signals.py", line 38, in _get_user_if_authenticated
    if request.user.is_authenticated:
AttributeError: 'NoneType' object has no attribute 'user'

Expected Behavior

Job to run successfully to completion just as it would if invoked via the UI or REST API

Observed Behavior

Job aborts and is cleaned up.

Initial Analysis

The runjob command calls:

        job_result = JobResult.enqueue_job(
            run_job,
            job_class.class_path,
            job_content_type,
            None,
            data={},
            request=None,  #  <-------<< important
            commit=options["commit"],
        )

JobResult.enqueue_job passes the provided request (in this case None) as a parameter to the enqueued run_job function.

When run_job runs with commit=True, it calls with change_logging(request): which enables change-logging for all DB changes triggered by the job via the _handle_changed_object signal.

_handle_changed_object expects a valid request object that it can retrieve the calling user and request-id from, but since it's None, an AttributeError is thrown.

Possible solutions:

1. In runjob, create a mock Request object via web_request_context and pass that instead of None
2. Enhance _handle_changed_object to gracefully handle a null Request.

IMO option 1 is probably better.