Nerdlet369 commented on issue #25061: URL: https://github.com/apache/airflow/issues/25061#issuecomment-6110443262
Submitted #74558 which documents both points raised here: * Square-bracket indexing on an `XComArg` (e.g. `params['list']`) references a separate XCom pushed by the upstream task under that key, rather than doing dictionary access on the return value. * Mapping can only expand against a task's *return value*, so `expand()` over an indexed `XComArg` fails with `ValueError: cannot map over XCom with custom key`. A warning with the failure and the workaround (add an intermediate task that returns the value) was added to the task-mapping page, plus a short note where the indexed syntax is first shown. Feedback welcome. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
