Callbacks and ErrbacksΒΆ
All tasks accept a url_callback
and url_errback
argument, that allows
to specify a HTTP endpoint that will be called when the task is complete.
This alleviates the need to poll POST /v2/status
to check if a task was
completed and simplifies asynchronous code if you need to queue many tasks at
once.
The callback endpoint will receive a POST containing the full task status as
soon as the task ends (the same JSON that you would get on
POST /v2/status
). Note that the request is not form-encoded, the POST
request body contains directly the status in JSON.
Warning
If you poll POST /v2/status
just after receiving the callback, it
will most likely return an “executing” status. This is expected, because it
takes some time for the status to propagate to the database. This is also
unneeded, since the final status is contained in the callback request body.