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kaxilnaik pushed a commit to branch v3-0-test
in repository https://gitbox.apache.org/repos/asf/airflow.git
The following commit(s) were added to refs/heads/v3-0-test by this push:
new 382b9f67ad8 Add note on XCom pull behaviour change (#49546)
382b9f67ad8 is described below
commit 382b9f67ad849bcfb3ac905ac025d7f802c2b0ec
Author: Kaxil Naik <[email protected]>
AuthorDate: Tue Apr 22 17:00:55 2025 +0530
Add note on XCom pull behaviour change (#49546)
related: https://github.com/apache/airflow/issues/49540
(cherry picked from commit 3ccbcff2e25acbcafcb710a200b78e29ddc7a827)
---
RELEASE_NOTES.rst | 35 +++++++++++++++++++++++++++++++++--
reproducible_build.yaml | 4 ++--
2 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/RELEASE_NOTES.rst b/RELEASE_NOTES.rst
index 8324131e799..f5197b2973b 100644
--- a/RELEASE_NOTES.rst
+++ b/RELEASE_NOTES.rst
@@ -332,8 +332,11 @@ aligning with the broader asset-aware execution model
introduced in Airflow 3.0.
``inlet_events`` may need to update logic that assumes the previous structure.
-Predictable Behaviour of ``xcom_pull``
-""""""""""""""""""""""""""""""""""""""
+
+Behaviour change in ``xcom_pull``
+"""""""""""""""""""""""""""""""""
+
+**Pulling without setting ``task_ids``**:
In Airflow 2, the ``xcom_pull()`` method allowed pulling XComs by key without
specifying task_ids, despite the fact that the underlying
DB model defines task_id as part of the XCom primary key. This created
ambiguity: if two tasks pushed XComs with the same key,
@@ -351,6 +354,34 @@ Should be updated to::
kwargs["ti"].xcom_pull(task_ids="task1", key="key")
+**Return Type Change for Single Task ID**:
+
+In Airflow 2, when using ``xcom_pull()`` with a single task ID in a list
(e.g., ``task_ids=["task1"]``), it would return a ``LazyXComSelectSequence``
+object containing one value. In Airflow 3.0.0, this behavior was changed to
return the value directly.
+
+So, if you previously used:
+
+.. code-block:: python
+
+ xcom_values = kwargs["ti"].xcom_pull(task_ids=["task1"], key="key")
+ xcom_value = xcom_values[0] # Access the first value
+
+You would now get the value directly, rather than a sequence containing one
value.
+
+.. code-block:: python
+
+ xcom_value = kwargs["ti"].xcom_pull(task_ids=["task1"], key="key")
+
+The previous behaviour (returning list when passed a list) will be restored in
Airflow 3.0.1 to maintain backward compatibility.
+
+However, it is recommended to be explicit about your intentions when using
``task_ids`` (after the fix in 3.0.1):
+
+- If you want a single value, use ``task_ids="task1"``
+- If you want a sequence, use ``task_ids=["task1"]``
+
+This makes the code more explicit and easier to understand.
+
+
Removed Configuration Keys
"""""""""""""""""""""""""""
diff --git a/reproducible_build.yaml b/reproducible_build.yaml
index 3ed76c96ba9..e8a278565cd 100644
--- a/reproducible_build.yaml
+++ b/reproducible_build.yaml
@@ -1,2 +1,2 @@
-release-notes-hash: 4d3a20b56440122fcbd72bf1b8c9020e
-source-date-epoch: 1745314549
+release-notes-hash: 07533055cb46f0d05c39b200665aeb61
+source-date-epoch: 1745320897
