Wow, just reading it, wasn't even aware of that behavior which is indeed "dangerous". I like the proposal, so I'm in favor! ________________________________ From: Jens Scheffler <[email protected]> Sent: Tuesday, May 12, 2026 21:06 To: [email protected] <[email protected]> Subject: Re: [DISCUSS] New Ruff rule to enforce explicit multiple_outputs when a task outputs a dict
EXTERNAL MAIL: Indien je de afzender van deze e-mail niet kent en deze niet vertrouwt, klik niet op een link of open geen bijlages. Bij twijfel, stuur deze e-mail als bijlage naar [email protected]<mailto:[email protected]>. Sounds like a good idea (also for me) 80% of users (I know) are not aware about that feature at all I think. On 12.05.26 11:53, Wei Lee wrote: > Yep, I like this idea. I was quite surprised to see this difference in > behavior. > > Best, > Wei > > Dev-iL <[email protected]> 於 2026年5月12日週二 下午4:05寫道： > >> Hi everyone, >> The context for this discussion is a recent PR which applied AIR201-like >> replacements to the codebase that had to be reverted [1]. >> It turns out that using task.output["key"] in place of {{ >> xcom_pull('task')['key'] }} is only correct when `multiple_outputs` is >> True. Which brings me to the matter at hand: the default value of >> `multiple_outputs` is not constant, and is inferred based on the presence >> of type hints, for example: >> >> @task >> def a(): # multiple_outputs = False >> return {"x": 1} >> >> @task >> def b() -> dict: # multiple_outputs = True ← inferred >> return {"x": 1} >> >> While the effects of multiple_outputs are mentioned in the docs [2], the >> effect of the type hint on functionality is, at best, implied [3]. Thus, an >> unsuspecting user adding type hints might not expect the change in >> functionality they will later observe. >> >> Without getting into whether multiple_outputs inference is good UX, I'd >> like to propose a new Ruff rule, which will detect when a task's output is >> either a dict or the task callable is annotated with a dict return type, >> and tell the user to specify the multiple_outputs value explicitly. >> Such a rule will have several benefits: 1) Make the intent of the Dag >> author explicit; 2) Robustify the code to future changes modifying the >> inference logic; 3) Increase awareness of `multiple_outputs`. >> >> Let me know what you think. >> >> Best, >> Dev-iL >> >> [1]: >> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fapache%2Fairflow%2Fpull%2F66712%23issuecomment-4424585768&data=05%7C02%7Cdavid.blain%40infrabel.be%7Ccf82ee9c4af347491e8408deb0598a2c%7Cb82bc314ab8e4d6fb18946f02e1f27f2%7C0%7C0%7C639142095795245565%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=RjWJY0vK7ZevUQXcXwj6rPJ4CbFraM83DtWM7WXO6AI%3D&reserved=0<https://github.com/apache/airflow/pull/66712#issuecomment-4424585768> >> [2]: >> >> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fairflow.apache.org%2Fdocs%2Fapache-airflow%2Fstable%2Ftutorial%2Ftaskflow.html%23step-2-write-your-tasks-with-task&data=05%7C02%7Cdavid.blain%40infrabel.be%7Ccf82ee9c4af347491e8408deb0598a2c%7Cb82bc314ab8e4d6fb18946f02e1f27f2%7C0%7C0%7C639142095795275996%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=pcl0Sj2by9%2FzMbJzYRGb5XSxifhM98spwwCE45L6sb8%3D&reserved=0<https://airflow.apache.org/docs/apache-airflow/stable/tutorial/taskflow.html#step-2-write-your-tasks-with-task> >> [3]: >> >> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fairflow.apache.org%2Fdocs%2Fapache-airflow%2Fstable%2Fhowto%2Fcreate-custom-decorator.html%23optional-adding-ide-auto-completion-support&data=05%7C02%7Cdavid.blain%40infrabel.be%7Ccf82ee9c4af347491e8408deb0598a2c%7Cb82bc314ab8e4d6fb18946f02e1f27f2%7C0%7C0%7C639142095795287436%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=717zhm64rvkeb5%2BRFsLJrejcW3Cw6bH5PmWguv8E4D8%3D&reserved=0<https://airflow.apache.org/docs/apache-airflow/stable/howto/create-custom-decorator.html#optional-adding-ide-auto-completion-support> >> --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
