XCom_pull of multiple task_ids not returning the list values

[edulauer]

Apache Airflow version

2.10.0

If "Other Airflow 2 version" selected, which one?

No response

What happened?

When passing a list of task IDs to the task_ids argument in task_instance.xcom_pull, instead of receiving a list of values returned by each task, you might encounter a string with the value 'LazySelectSequence'."
In older versions of Airflow, such as 2.9.3, this issue did not occur.

What you think should happen instead?

It should return a list of values pushed by each task mentioned in the task_ids argument

How to reproduce

with DAG as dag:

push_task = PythonOperator(
    task_id='push_task',
    python_callable=lambda: 'Hello, World!')

push_task_2 = PythonOperator(
    task_id='push_task_2',
    python_callable=lambda: 'Hello, World 2!')

def pull_function(**kwargs):
    ti = kwargs['ti']
    msg = ti.xcom_pull(task_ids=['push_task', 'push_task_2'])
    print("received message: '%s'" % msg)

pull_task = PythonOperator(
    task_id='pull_task',
    python_callable=pull_function,
    provide_context=True,
)

Operating System

Debian GNU/Linux 12

Versions of Apache Airflow Providers

No response

Deployment

Docker-Compose

Deployment details

FROM apache/airflow:2.10.0-python3.10

Anything else?

In older versions of Airflow, such as 2.9.3, this issue did not occur.

Error log:
[2024-09-03, 17:48:50 -03] {logging_mixin.py:190} INFO - received message: 'LazySelectSequence([2 items])'

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[boring-cyborg]

Thanks for opening your first issue here! Be sure to follow the issue template! If you are willing to raise PR to address this issue please do so, no need to wait for approval.

[FelipeRamos-neuro]

I recently ran into this same behavior using xcom_pull with jinja and can confirm that this is also happening in version 2.10.2.

[johncmerfeld]

I believe the root cause of this is #39426 but I don't know if my recent PR (#43978) will fix it