michal-cech opened a new issue, #25061:
URL: https://github.com/apache/airflow/issues/25061
### Apache Airflow version
2.3.3 (latest released)
### What happened
When tasks return dictionary value, it is possible to access the value on
the DAG level by using `return_value['key']`. This does not seem to be possible
when using the newly added `expand` functionality. It fails to load the DAG
with (see example below): `ValueError: cannot map over XCom with custom key
'list' from <Task(_PythonDecoratedOperator): params>`
### What you think should happen instead
I think Airflow should behave in a consistent way while using
```
task(return_value['something'])
```
and
```
task.expand(arg=return_value['something'])
```
### How to reproduce
from datetime import datetime
from airflow.decorators import dag, task
import pendulum
@dag(
default_args={
'owner': 'airflow',
'start_date': pendulum.datetime(2022, 7, 14, tz="Europe/Prague"),
'depends_on_past': False,
'retries': 0,
},
schedule_interval="* * * * *",
max_active_runs=1,
)
def test():
@task(multiple_outputs=True)
def params():
return {"a": 1, "b": 1, "list": [1, 2, 3]}
parameters = params()
@task
def print_list(list):
return list
@task
def print_elements(element):
return element
#this works
print_list(parameters['list'])
#this also works
print_elements.expand(element=[1,2,3])
#this does not
print_elements.expand(element=parameters['list'])
test_dag = test()
### Operating System
Ubuntu 20.0.4
### Versions of Apache Airflow Providers
_No response_
### Deployment
Docker-Compose
### 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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