amoghrajesh opened a new pull request, #53814:
URL: https://github.com/apache/airflow/pull/53814
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closes: https://github.com/apache/airflow/issues/53432
## Problem
The `BaseXCom.get_all()` method was directly calling deserialize() from the
serialization module instead of using the overridable cls.deserialize_value()
method. This broke custom XCom backends that rely on overriding
`deserialize_value()` to implement custom deserialization logic.
Example of broken behavior:
```
class CustomXCom(BaseXCom):
@classmethod
def deserialize_value(cls, result):
# Custom logic that was being bypassed
return f"custom_prefix:{super().deserialize_value(result)}"
# get_one() worked correctly - called CustomXCom.deserialize_value()
# get_all() was broken - bypassed CustomXCom.deserialize_value()
```
## Root Cause
The issue comes from inconsistent deserialization patterns:
- get_one() correctly calls `cls.deserialize_value(msg)` where msg is an
`XComResult` with a value attribute
- get_all() was calling `deserialize(msg.root)` directly, where `msg.root`
is a `list[JsonValue]`
The deserialize_value() method expects an object with a value attribute, but
the sequence slice returns a flat list of serialized values.
- Applied the same wrapper pattern already established in lazy_sequence.py
- Its a lightweight wrapper that exposes `_XComValueWrapper` that provides
`.value` as needed
## Testing
DAG:
```
from airflow import DAG
from airflow.providers.standard.operators.python import PythonOperator
def push_to_xcom(**kwargs):
value = "Hello, XCom!"
return value
def push_to_xcom2(**kwargs):
value = "Hello, XCom2!"
return value
def pull_from_xcom(**kwargs):
ti = kwargs['ti']
xcom_value = ti.xcom_pull(task_ids=["push_xcom_task", "push_xcom_task2"])
print(f"Retrieved XCom Value: {xcom_value}")
with DAG(
'xcom_example',
schedule=None,
catchup=False,
) as dag:
push_xcom_task = PythonOperator(
task_id='push_xcom_task',
python_callable=push_to_xcom,
)
push_xcom_task2 = PythonOperator(
task_id='push_xcom_task2',
python_callable=push_to_xcom2,
)
pull_xcom_task = PythonOperator(
task_id='pull_xcom_task',
python_callable=pull_from_xcom,
)
push_xcom_task >> push_xcom_task2 >> pull_xcom_task
```
Write a custom xcom backend:
```
from airflow.sdk.bases.xcom import BaseXCom
class MyXCom(BaseXCom):
@classmethod
def deserialize_value(self, value):
return {"from": "custom xcom"}
```
Run breeze with:
```
export PYTHONPATH="/files/plugins:$PYTHONPATH"
export AIRFLOW__CORE__XCOM_BACKEND="myxcom.MyXCom"
```
Validate if the right one got loaded:
```
>>> from airflow.sdk.execution_time.xcom import XCom
>>>
>>> XCom
<class 'myxcom.MyXCom'>
>>> XCom.__name__
'MyXCom'
```
Run the dag:
Push task
<img width="1721" height="667" alt="image"
src="https://github.com/user-attachments/assets/29ecfe09-b801-40d6-b34f-0f7dc2ebd080";
/>
Pull task
<img width="1721" height="667" alt="image"
src="https://github.com/user-attachments/assets/d0d54b93-7ab3-4e6a-8c0a-47a77394a4fd";
/>
<!-- Please keep an empty line above the dashes. -->
---
**^ Add meaningful description above**
Read the **[Pull Request
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for more information.
In case of fundamental code changes, an Airflow Improvement Proposal
([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvement+Proposals))
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In case of a new dependency, check compliance with the [ASF 3rd Party
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In case of backwards incompatible changes please leave a note in a
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