Desdroid opened a new issue, #55759:
URL: https://github.com/apache/airflow/issues/55759
### Apache Airflow version
3.0.6
### If "Other Airflow 2 version" selected, which one?
_No response_
### What happened?
I think there is an issue using task groups in combination with dynamic task
mapping.
It seems like one cannot map again over the output of a mapped task_group.
Given this example DAG the task add_10 in the task group will fail with an
UnmappableXComTypePushed: unmappable return type 'int' exception.
```python
import pendulum
from datetime import datetime
from airflow.sdk import task, task_group, dag
import logging
logger = logging.getLogger(__name__)
@dag(
dag_id="test_dag",
dag_display_name="test dynamic task group mapping",
schedule=None,
start_date=datetime(
2021, 6, 27, 0, 0, 0, tzinfo=pendulum.timezone("Europe/Berlin")
),
catchup=False,
description="1.0.0",
)
def test_dag():
@task
def get_nums():
return [1, 2, 3, 4, 5, 6, 7, 8]
@task
def times_2(num):
return num * 2
@task
def add_10(num):
return num + 10
@task
def log_num(text, num):
logger.info(f"{text}{num}")
@task_group
def process_number(num):
_times_2 = times_2(num)
_add_10 = add_10(_times_2)
return _add_10
_get_nums = get_nums()
# _times_2 = times_2.expand(num=_get_nums)
# _add_10 = add_10.expand(num=_times_2)
_processed_numbers = process_number.expand(num=_get_nums)
log_num.partial(text="Got number: ").expand(num=_processed_numbers)
instance = test_dag()
```
### What you think should happen instead?
The returned ints of the mapped task group should be collected into a list
and the log_num task should be executed once for each number in the list.
Similar as documented here:
https://airflow.apache.org/docs/apache-airflow/stable/authoring-and-scheduling/dynamic-task-mapping.html#depending-on-a-mapped-task-group-s-output
Or is this just a misunderstanding from my side on how dynamic task mapping
works?
### How to reproduce
Copy & Paste the given DAG
### Operating System
Official Airflow Docker Image airflow:slim-3.0.6
### Versions of Apache Airflow Providers
-
### Deployment
Official Apache Airflow Helm Chart
### Deployment details
_No response_
### Anything else?
_No response_
### Are you willing to submit PR?
- [ ] Yes I am willing to submit a PR!
### Code of Conduct
- [x] I agree to follow this project's [Code of
Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
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