Have a problem triggering flow-runs from completed flows with variable parameters passed. I can trig...

Scott White

08/29/2022, 1:34 PM

Have a problem triggering flow-runs from completed flows with variable parameters passed. I can trigger the flows just fine, but the parameters are not getting passed correctly. Can you share the code syntax to trigger a new flow with parameters using

prefect<2.0

and the functional API? I will share the pseudo-code and syntax in a reply.

✅ 1

Scott White

08/29/2022, 1:45 PM

Copy code

import prefect
from prefect.tasks.prefect import create_flow_run

def get_update_date():
    return '2022-01-01'

def trigger_flow(**kwargs):
    create_flow_run.run(
        flow_name='flow-2'
        project_name='test',
        parameters={'update_date': kwargs.get('update_date')}
    )

get_update_date = prefect.task(get_update_date)
trigger_flow = prefect.task(trigger_flow)

with prefect.Flow('flow-1') as flow:
    update_date = get_update_date()
    trigger_flow(update_date=update_date)

Scott White

08/29/2022, 1:48 PM

Flow 2:

Copy code

import prefect

update_date = prefect.Parameter('update_date', default=None)

def print_date(update_date):
   prefect.logger(f'{update_date}')

print_date = prefect.task(print_date)

with prefect.Flow('flow-2') as flow:
    print_date()

Scott White

08/29/2022, 1:48 PM

In this case, the flow-2 will print

None

when it is triggered by

flow-1

but if I trigger

flow-2

manually with a hard-coded

update_date

it will print just fine

Jeff Hale

08/29/2022, 3:51 PM

Tasks need to be called within Flows. This example and this thread and associated resources might be helpful.

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