fix Inconsistent XCom Return Type in Mapped Task Groups with Dynamic … by henry3260 · Pull Request #59104 · apache/airflow

henry3260 · 2025-12-05T17:41:18Z

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…Task Mapping

jason810496

Thanks for the PR!

It would be nice to add the corresponding unit tests as well, thanks!

jason810496

Sorry for the delayed review, thanks for the fix!

LGTM overall, but we still need some refactor on the test to verify the expected behavior, thanks!

henry3260 · 2026-01-15T10:14:52Z

@jason810496 @uranusjr I've addressed the comments. Please let me know if there's anything else blocking the merge.
Appreciate any comments! :)

jason810496

LGTM. Not sure if @uranusjr has any additional comments.

AutomationDev85 · 2026-02-20T09:11:41Z

Hi all, we hit the same issue with Airflow 3.1.7. I don’t think the changes in this PR are sufficient, though. In RuntimeTaskInstance there’s also a check that returns a single item instead of the list when the XCom list has only one element (see https://github.com/apache/airflow/blob/main/task-sdk/src/airflow/sdk/execution_time/task_runner.py#L392). Shouldn’t that be updated too?

jscheffl · 2026-02-21T18:16:53Z

Oh, this is stale since a while but something I'd expected basic. @uranusjr can you re-review?

Not sure the other problem in task_runner.py as mentioned above can also be a spearate PR not to delay here further. But see the same inconsistency there as well and needs to be fixed.

henry3260 · 2026-02-21T18:25:30Z

Oh, this is stale since a while but something I'd expected basic. @uranusjr can you re-review?

Not sure the other problem in task_runner.py as mentioned above can also be a spearate PR not to delay here further. But see the same inconsistency there as well and needs to be fixed.

yeah, maybe I can open another one to address inconsistent issue mentioned abbove.

vatsrahul1001 · 2026-03-02T05:35:56Z

Oh, this is stale since a while but something I'd expected basic. @uranusjr can you re-review?

Not sure the other problem in task_runner.py as mentioned above can also be a spearate PR not to delay here further. But see the same inconsistency there as well and needs to be fixed.

@uranusjr could you re-review?

jscheffl · 2026-03-02T20:03:06Z

@henry3260 can you adjust to get it into 3.1.8 as a fix?

vatsrahul1001 · 2026-03-03T04:17:10Z

@henry3260 can you adjust to get it into 3.1.8 as a fix?

Yeah @henry3260, planning to cut 3.1.8rc1 soon, appreciate it if you can implement the latest review comments

henry3260 · 2026-03-03T04:33:55Z

@henry3260 can you adjust to get it into 3.1.8 as a fix?

Yeah @henry3260, planning to cut 3.1.8rc1 soon, appreciate it if you can implement the latest review comments

OK, I will take a look!

Copilot

Pull request overview

This PR addresses inconsistent TaskInstance.xcom_pull() return types for mapped tasks by returning a LazyXComSelectSequence when pulling mapped XComs (map_index >= 0) without explicitly specifying map_indexes, and adds unit tests to validate mapped vs. unmapped behavior.

Changes:

Update TaskInstance.xcom_pull() to return LazyXComSelectSequence for mapped XComs when map_indexes is not specified.
Add unit tests asserting unmapped pulls return a single deserialized value and mapped pulls return a lazy sequence.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
`airflow-core/src/airflow/models/taskinstance.py`	Adjusts `xcom_pull` to consistently return a lazy sequence for mapped XComs in the single-task pull path.
`airflow-core/tests/unit/models/test_taskinstance.py`	Adds tests covering unmapped vs. mapped `xcom_pull` return types.

henry3260 · 2026-03-10T08:02:54Z

I think this PR is good to go, but let me know if I missed anything.

…ith Dynamic … (#59104) * fix Inconsistent XCom Return Type in Mapped Task Groups with Dynamic Task Mapping * add unit test for xcom_pull * remove asc func (cherry picked from commit df2e2b8) Co-authored-by: Henry Chen <[email protected]>

github-actions · 2026-03-10T19:41:11Z

Backport successfully created: v3-1-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	v3-1-test

…ith Dynamic … (#59104) (#63293) * fix Inconsistent XCom Return Type in Mapped Task Groups with Dynamic Task Mapping * add unit test for xcom_pull * remove asc func (cherry picked from commit df2e2b8) Co-authored-by: Henry Chen <[email protected]>

apache#59104) * fix Inconsistent XCom Return Type in Mapped Task Groups with Dynamic Task Mapping * add unit test for xcom_pull * remove asc func

…ith Dynamic … (#59104) (#63293) * fix Inconsistent XCom Return Type in Mapped Task Groups with Dynamic Task Mapping * add unit test for xcom_pull * remove asc func (cherry picked from commit df2e2b8) Co-authored-by: Henry Chen <[email protected]>

henry3260 requested review from XD-DENG and ashb as code owners December 5, 2025 17:41

fix Inconsistent XCom Return Type in Mapped Task Groups with Dynamic …

16596fb

…Task Mapping

henry3260 force-pushed the fix-Xcom-type branch from b70e671 to 16596fb Compare December 5, 2025 19:11

Merge branch 'main' into fix-Xcom-type

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jason810496 reviewed Dec 6, 2025

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henry3260 requested a review from jason810496 December 16, 2025 04:05

jason810496 reviewed Dec 22, 2025

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uranusjr reviewed Dec 22, 2025

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Comment thread airflow-core/src/airflow/models/taskinstance.py Outdated

uranusjr reviewed Dec 22, 2025

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Comment thread airflow-core/src/airflow/models/taskinstance.py Outdated

henry3260 force-pushed the fix-Xcom-type branch 6 times, most recently from 5631f70 to d11f843 Compare December 29, 2025 18:04

henry3260 requested a review from uranusjr December 29, 2025 18:56

jason810496 approved these changes Jan 16, 2026

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jason810496 requested a review from Lee-W February 3, 2026 03:25

eladkal added this to the Airflow 3.1.8 milestone Feb 3, 2026

eladkal added the backport-to-v3-1-test label Feb 3, 2026

uranusjr reviewed Mar 2, 2026

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Comment thread airflow-core/src/airflow/models/taskinstance.py Outdated

henry3260 force-pushed the fix-Xcom-type branch from d11f843 to 958bd74 Compare March 3, 2026 09:27

vatsrahul1001 modified the milestones: Airflow 3.1.8, Airflow 3.1.9 Mar 3, 2026

henry3260 force-pushed the fix-Xcom-type branch 3 times, most recently from 3490f4f to c026e6a Compare March 3, 2026 13:29

add unit test for xcom_pull

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Copilot AI review requested due to automatic review settings March 3, 2026 19:23

henry3260 force-pushed the fix-Xcom-type branch from c026e6a to 16ffe7a Compare March 3, 2026 19:23

Copilot started reviewing on behalf of henry3260 March 3, 2026 19:23 View session

Merge branch 'main' into fix-Xcom-type

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Copilot AI reviewed Mar 3, 2026

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Comment thread airflow-core/src/airflow/models/taskinstance.py

Comment thread airflow-core/tests/unit/models/test_taskinstance.py

henry3260 force-pushed the fix-Xcom-type branch from 17a542b to 48ff18c Compare March 4, 2026 03:05

uranusjr approved these changes Mar 4, 2026

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remove asc func

5123477

henry3260 force-pushed the fix-Xcom-type branch from 48ff18c to 5123477 Compare March 4, 2026 13:58

jscheffl approved these changes Mar 10, 2026

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jscheffl merged commit df2e2b8 into apache:main Mar 10, 2026
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henry3260 commented Mar 10, 2026

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github-actions Bot commented Mar 10, 2026

Backport successfully created: v3-1-test

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vatsrahul1001 commented Mar 2, 2026 •

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