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Fix XCom deserialization for mapped tasks with custom backend #50687

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Merged
amoghrajesh merged 1 commit into from
May 16, 2025
Merged

Fix XCom deserialization for mapped tasks with custom backend #50687

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5 changes: 2 additions & 3 deletions task-sdk/src/airflow/sdk/execution_time/lazy_sequence.py
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Original file line number Diff line number Diff line change
Expand Up @@ -140,10 +140,9 @@ def __getitem__(self, key: int | slice) -> T | Sequence[T]:
# if not reverse:
# rows.reverse()
# return rows

from airflow.sdk.bases.xcom import BaseXCom
from airflow.sdk.execution_time.comms import GetXComSequenceItem, XComResult
from airflow.sdk.execution_time.task_runner import SUPERVISOR_COMMS
from airflow.sdk.execution_time.xcom import XCom

with SUPERVISOR_COMMS.lock:
source = (xcom_arg := self._xcom_arg).operator
Expand All @@ -161,7 +160,7 @@ def __getitem__(self, key: int | slice) -> T | Sequence[T]:

if not isinstance(msg, XComResult):
raise IndexError(key)
return BaseXCom.deserialize_value(msg)
return XCom.deserialize_value(msg)


def _coerce_index(value: Any) -> int | None:
Expand Down
34 changes: 34 additions & 0 deletions task-sdk/tests/task_sdk/execution_time/test_lazy_sequence.py
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@

import pytest

import airflow
from airflow.sdk.bases.xcom import BaseXCom
from airflow.sdk.exceptions import ErrorType
from airflow.sdk.execution_time.comms import (
ErrorResponse,
Expand All @@ -30,6 +32,9 @@
XComResult,
)
from airflow.sdk.execution_time.lazy_sequence import LazyXComSequence
from airflow.sdk.execution_time.xcom import resolve_xcom_backend

from tests_common.test_utils.config import conf_vars


@pytest.fixture
Expand All @@ -52,6 +57,12 @@ def lazy_sequence(mock_xcom_arg, mock_ti):
return LazyXComSequence(mock_xcom_arg, mock_ti)


class CustomXCom(BaseXCom):
@classmethod
def deserialize_value(cls, xcom):
return f"Made with CustomXCom: {xcom.value}"


def test_len(mock_supervisor_comms, lazy_sequence):
mock_supervisor_comms.get_message.return_value = XComCountResponse(len=3)
assert len(lazy_sequence) == 3
Expand Down Expand Up @@ -109,6 +120,29 @@ def test_getitem_index(mock_supervisor_comms, lazy_sequence):
]


@conf_vars({("core", "xcom_backend"): "task_sdk.execution_time.test_lazy_sequence.CustomXCom"})
def test_getitem_calls_correct_deserialise(mock_supervisor_comms, lazy_sequence):
mock_supervisor_comms.get_message.return_value = XComResult(key="return_value", value="some-value")

xcom = resolve_xcom_backend()
assert xcom.__name__ == "CustomXCom"
airflow.sdk.execution_time.xcom.XCom = xcom

assert lazy_sequence[4] == "Made with CustomXCom: some-value"
assert mock_supervisor_comms.send_request.mock_calls == [
call(
log=ANY,
msg=GetXComSequenceItem(
key="return_value",
dag_id="dag",
task_id="task",
run_id="run",
offset=4,
),
),
]


def test_getitem_indexerror(mock_supervisor_comms, lazy_sequence):
mock_supervisor_comms.get_message.return_value = ErrorResponse(
error=ErrorType.XCOM_NOT_FOUND,
Expand Down