hterik opened a new issue, #62988:
URL: https://github.com/apache/airflow/issues/62988
### Description
When triggering a dag through `TriggerDagRunOperator`, it would be useful
for the dag that initiated the trigger to fetch information produced in the
triggered dag .
Example:
```python
@dag()
def child_dag():
@task
def run():
return "hello world"
run()
@dag()
def top_dag():
@task
def postprocess(trigger_task):
context = get_current_context()
child_run_id =
context["task_instance"].xcom_pull(task_ids="trigger_child",
key="trigger_run_id")
child_dag_return_value = context["task_instance"].xcom_pull(
dag_id="child_dag",
task_id="run",
DESIRED_PARAMETER_TO_SET_RUN_ID=child_run_id #
<---------------------------------------
)
assert child_dag_return_value == "hello world"
t_trigger = TriggerDagRunOperator(
task_id="trigger_child",
trigger_dag_id="child_dag",
wait_for_completion=True
)
postprocess(t_trigger)
```
While `xcom_pull` does allow fetching from a different `dag_id`, it has no
parameter to control the exact `run_id`, it assumes the `execution_date` is the
same, or with `include_prior_dates=True` it takes the latest found. (In the
example above this doesn't make any difference because the return value is
static, in more realistic scenarios, the output is based on parameters passed
from the top_dag and need to be in sync)
### Use case/motivation
_No response_
### Related issues
_No response_
### Are you willing to submit a 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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