ninsbl opened a new issue, #69117:
URL: https://github.com/apache/airflow/issues/69117
### Under which category would you file this issue?
Airflow Core
### Apache Airflow version
Airflow 3.2.1
### What happened and how to reproduce it?
I have a DAG that produces partitioned Assets. It contains a dynamicaly
mapped task group of which one task has an Asset defined an outlet and emitts
_AssetEvents_ for each expanded instance of the TaskGroup.
When I used `yield Metadata` the downstream DAG was triggered by each
_AssetEvent_, so one run of the source DAG could result in e.g. three _DagRuns_
of the downstream DAG.
However, when I upgraded from Airflow 2.10.4 to Airflow 3.2.1, I also
switched to attaching extra information to _AssetEvents_ with
`outlet_events[ASSET].extra`.
The first issue I encountered was that _AssetEvents_ did not show up in the
UI, when `outlet_events` wasn`t a keyword only argument in the producing task
function. E.g.
```
def producing_function(input: str, outlet_events=None):
"""Example producing task"""
`outlet_events[ASSET].extra = {"section": "XY"}
```
Did not show AssetEvents. But it triggered the downstream DAG that then hang
because the AssetEvent was not accessible.
Making _outlet_events_ a keyword argument like this:
```
def producing_function(input: str, *, outlet_events=None):
"""Example producing task"""
`outlet_events[ASSET].extra = {"section": "XY"}
```
produced visible _AssetEvents_. The downstream DAG gets triggered only once
but shows all three _AssetEvents_ with the attached extra metadata from the
three mapped taskgroup instances in the producing DAG.
When I use `yield Metadata(ASSET, {"section": "XY"})` in the producing task,
each _TaskInstance_ triggers a DagRun of the downstream DAG with the extra
metadata properly attached (which I expected to happen and how it was before).
The documentation indicates that `yield Metadata` and
`outlet_events[ASSET].extra` are equivalent:
https://airflow.apache.org/docs/apache-airflow/3.2.2/authoring-and-scheduling/assets.html#attaching-extra-information-to-an-emitting-asset-event
For partitioned assets, they clearly are not.
### What you think should happen instead?
The difference in behavior between `yield Metadata(ASSET, {"section":
"XY"})` and `outlet_events[ASSET].extra = {"section": "XY"}` - at least for
partitioned DAGs - should be clearly documented and outlet_events should be
properly produced also when outlet_events are not accessed as keyword only
arguments.
### Operating System
Ubuntu 24.04
### Deployment
Docker-Compose
### Apache Airflow Provider(s)
_No response_
### Versions of Apache Airflow Providers
_No response_
### Official Helm Chart version
Not Applicable
### Kubernetes Version
_No response_
### Helm Chart configuration
_No response_
### Docker Image customizations
Not Applicable
### Anything else?
_No response_
### Are you willing to submit PR?
- [x] 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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