Mastering Flask Web Development - Second Edition

Chain

The chain function takes task signatures and passes the value of each result to the next value in the chain, returning one result, as follows:

>>> from celery import chain
>>> sig = chain(multiply.s(10, 10), multiply.s(4), multiply.s(20))
# same as above
>>> sig = (multiply.s(10, 10) | multiply.s(4) | multiply.s(20))
>>> result = sig.delay()
>>> result.get()
8000
  

Chains and partials can be taken a bit further. Chains can be used to create new functions when using partials, and chains can be nested as follows:

# combining partials in chains >>> func = (multiply.s(10) | multiply.s(2)) >>> result = func.delay(16) >>> result.get() 320# chains can be nested >>> func = ( multiply.s(10) | multiply.s(2) | (multiply.s(4) | multiply.s(5)) ) ...