Hi all, is there a canonical way for dynamic workflows to collect only succesful sub-tasks? I have a task A that may or may not succeed. I have a dynamic workflow D that launches a bunch of instances of A, with various parameters. I want to collect only the successful results of A, aggregate them, and then return that result from D. I've seen discussions of an

allowed_failure_ratio

parameter, but that seems to have been removed when moving away from sdk tasks. There's the

WorkflowFailurePolicy

, but while that would allow every sub-task to run, it doesn't seem that it would allow D to run. My current approach is to wrap A in a

try/except

that returns an empty result, but D can't inspect the results to ignore A, so the aggregator has to decide if this is a valid result or not. Does anyone have a better idea for how to return what is effectively a "I failed, but it's okay, just ignore me" signal?

no you’re going to need an aggregator some how

Cool, that makes sense. Thanks! Just for my understanding - the reason it's like this is that the dynamic task is run at instantiation and then returns the DAG, and the actual promise objects don't get collected until that goes into another task?

that is what happens yeah, but the reason that propeller only knows how to pass inputs and outputs. it doesn’t know how to: pass if not None (or other things that people have asked for in the past like: add 1 to an output before passing it on. for small use-cases you can use conditional workflows