Celery task bad return when using update_state

Question

I have a celery task which updates it's state multiple times while it's running with:

current_task.update_state(state='STARTED', meta={'doing': "some message"},)

When this task returns:

return row  # row is a Django model instance

The return value I get:

>> res = task_above.delay()
>> res.result
u'16'

is only the object's id as a string, not the pickled object itself.

If i remove the update_state statements, I get the correct pickled object in the task's meta (AsyncResult.result)

How can I use update_state and get the same return value (pickled object)?

Answer 1

I'm surprised that you can get a pickled django model instance at all, considering pickle only supports python primitives. Are you absolutely sure that you are ever getting the django model instance as a pickled result? maybe it's not going thru celery and it's not pickled?

see [this SO answer] for more about pickling django model instances1.