Retrieve task result by id in Celery

Question

I am trying to retreive the result of a task which has completed. This works

from proj.tasks import add
res = add.delay(3,4)
res.get()
7
res.status
'SUCCESS'
res.id
'0d4b36e3-a503-45e4-9125-cfec0a7dca30'

But I want to run this from another application. So I rerun python shell and try:

from proj.tasks import add
res = add.AsyncResult('0d4b36e3-a503-45e4-9125-cfec0a7dca30')
res.status
'PENDING'
res.get() # Error

How can I retrieve the result?

Answer 1

It works using AsyncResult. (see this answer)

So first create the task:

from cel.tasks import add

res = add.delay(3,4)
print(res.status) # 'SUCCESS'
print(res.id) # '432890aa-4f02-437d-aaca-1999b70efe8d'

Then start another python shell:

from celery.result import AsyncResult
from cel.tasks import app

res = AsyncResult('432890aa-4f02-437d-aaca-1999b70efe8d',app=app)

print(res.state) # 'SUCCESS'
print(res.get()) # 7

Answer 2

This is due to RabbitMQ not actually storing the results. If you need the ability to get the results later on, use redis or SQL as the result backend.