[PRO] Job(my_celery).Except(this.task_on_exception) transition for Jobs

[snickell]

My flows use a LOT of Celery Jobs to process UI input that would take to long to run synchronously in the web process.

It would be very elegant if viewflow.contrib.celery.Job supported a special .Except(this.another_task) that was like .Next(), but used in case the celery job raises an Exception.

my_task = (
    Job(my_celery_job)
    .Except(this.on_my_task_fail)
    .Next(this.on_my_task_success)
)

[kmmbvnr]

Yep, it's a good idea.

But generally I think using any Exception a bit dangerous, but having specific TaskFailded exception would be good

[variable]

Hi I have created something similar, I have just started using viewflow few days ago, can you please verify my implementation?

https://stackoverflow.com/questions/58794582/django-viewflow-what-is-the-proper-way-to-handle-exceptions-in-handler/58795132#58795132

Like I mentioned in the solution, I cannot find a clean pass to pass the exception to the exception node activation unless in the exception node I use another custom activation to accept the extra constructor argument.

activation = mapping['node'].activate(prev_activation=self, token=self.task.token)
# wish I could just pass like
activation = mapping['node'].activate(prev_activation=self, token=self.task.token, exception=self.caught_exception)

[variable]

@snickell today I encountered the same need for celery job, so I added the CatchExceptionJob to do the same. I have updated my Stackoverflow answer.