👋 I have a question about Result/Target usage, I would like the target template to be based on the flow parameters - how would I do that? ``````

Hi @Rafał Wojdyła all values that are available in context should be available to the template! One of those being

parameters

. So if you have a flow that takes a

val

param you should be able to access it through

{parameters[val]}

👋 @josh yes, I have tried that, but run into an issue where default value of parameters are not in the context/parameters. is this by design?

Hmm I just ran a test and I was able to grab the default value from parameters. Target:

target="{parameters[val]}"

and the Parameter is

Parameter("val", default="asdf")

@josh which version of Prefect?

I am on the latest version

@josh I'm on

0.11.2

, could you pls post the code you have used?

Ah it’s possible that old version does not support it (FWIW the current version is

0.14.7

). Here is the code I am using:

from prefect import Flow, task, Parameter
from prefect.engine.results import LocalResult


@task(target="{parameters[val]}")
def get_data(val):
    return [val]


@task
def print_data(data):
    print(data)


with Flow(
    "using-targets",
    result=LocalResult(),
) as flow:
    val = Parameter("val", default="asdf")
    data = get_data(val)
    print_data(data)

flow.run()

@josh that was actually the problem (0.11.2 doesn't support defaults it seems). thanks. I have a quick follow up question please, I would like to create dependencies between Flows without registering any of them (which is doc here: https://docs.prefect.io/api/latest/tasks/prefect.html#running-dependent-flows). This is akin to luigi's

requires

on another task. Is this something that Prefect supports?

Hmm, without registering them?

@josh I see, so to create dependency between flows, right now one must register at least the upstream one (and use

StartFlowRun

)?

Yes

@josh and if I would like to depend on only one task out of another flow, is there a way to do that?

Some people achieve that by utilizing targets. For example: Flow A kicks off Flow B. Then B has a task that write some data to a target. Now you can have a task in Flow A that also looks at that same target and can act upon it. Other than that there isn’t yet fully first-class way of doing it

@josh I see. thanks all this was very helpful and I think it should be enough for me to make a decision