insomnes commented on code in PR #46728:
URL: https://github.com/apache/airflow/pull/46728#discussion_r1975397441
##########
task_sdk/src/airflow/sdk/execution_time/task_runner.py:
##########
@@ -289,27 +296,46 @@ def xcom_pull(
if task_ids is None:
# default to the current task if not provided
- task_ids = self.task_id
+ task_ids = [self.task_id]
elif isinstance(task_ids, str):
task_ids = [task_ids]
+
+ map_indexes_iterable: Iterable[int | None] = []
+ # If map_indexes is not provided, default to use the map_index of the
calling task
if isinstance(map_indexes, ArgNotSet):
- map_indexes = self.map_index
- elif isinstance(map_indexes, Iterable):
- # TODO: Handle multiple map_indexes or remove support
- raise NotImplementedError("Multiple map_indexes are not supported
yet")
+ map_indexes_iterable = [self.map_index]
+ elif isinstance(map_indexes, int) or map_indexes is None:
+ map_indexes_iterable = [map_indexes]
+ else:
+ map_indexes_iterable = map_indexes
log = structlog.get_logger(logger_name="task")
xcoms = []
- for t in task_ids:
+ # TODO: Execution API only allows working with a single map_index at a
time
+ # this is inefficient and leads to task_id * map_index requests to the
API.
+ # And we can't achieve the original behavior of XCom pull with
multiple tasks
+ # directly now.
+ # Original behavior may be achieved after `LazyXComSequence` is
finished?
+ #
+ # Original description:
+ #
+ # When pulling one single task (``task_id`` is *None* or a str) without
+ # specifying ``map_indexes``, the return value is inferred from whether
+ # the specified task is mapped. If not, value from the one single task
+ # instance is returned. If the task to pull is mapped, an iterator
(not a
+ # list) yielding XComs from mapped task instances is returned. In
either
+ # case, ``default`` (*None* if not specified) is returned if no
matching
+ # XComs are found.
+ for t_id, m_idx in product(task_ids, map_indexes_iterable):
Review Comment:
Correct me if I am looking at the wrong API, but the `get_xcom` method here:
https://github.com/apache/airflow/blob/main/airflow/api_fastapi/execution_api/routes/xcoms.py#L117
Returns only one XCom result by signature and as I understood through code
reading:
```python
# The xcom_query allows no map_index to be passed. This endpoint should
always return just a single item,
# so we override that query value
xcom_query = xcom_query.filter(BaseXCom.map_index == map_index)
# We use `BaseXCom.get_many` to fetch XComs directly from the database,
bypassing the XCom Backend.
# This avoids deserialization via the backend (e.g., from a remote
storage like S3) and instead
# retrieves the raw serialized value from the database. By not relying
on `XCom.get_many` or `XCom.get_one`
# (which automatically deserializes using the backend), we avoid
potential
# performance hits from retrieving large data files into the API server.
result = xcom_query.limit(1).first()
```
And `XComResult`, `XComResponse` are single-item models, am I missing
something? Will it be multiple inside the JSON? My manual tests showed that
with the current API call non-providing is not a working strategy, at least
back then. I will recheck.
> not passing a map index as "return all XComs for mapped tis"
This behavior is available at `get_xcom_entries` from public xcom API, and I
was targeting it in my initial variant, but after testing I understood that
different API is used and I cannot rely on this:
https://github.com/apache/airflow/blob/main/airflow/api_fastapi/core_api/routes/public/xcom.py#L109
Can you guide me here, what kind of behavior is expected from this method? I
will try to make it work via `LazySequence` if possible.
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