Bjorn Olsen created AIRFLOW-6170:
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Summary: BranchPythonOperator does not do XCom push of returned
value
Key: AIRFLOW-6170
URL: https://issues.apache.org/jira/browse/AIRFLOW-6170
Project: Apache Airflow
Issue Type: Improvement
Components: operators
Affects Versions: 1.10.6
Reporter: Bjorn Olsen
Assignee: Bjorn Olsen
BranchPythonOperator subclasses PythonOperator and this means that after it has
selected a branch we get a message like this:
[2019-12-04 08:39:59,960] \{python_operator.py:114} INFO - Done. Returned value
was: chosen_task
This returned value is from the execute() method. A user would expect the
returned value from this to be pushed to an XCOM but this does not happen due
to no return value from the BranchPythonOperator.
If we do an XCOM push of the result then we can use the decision made by
BranchPythonOperator in downstream tasks.
Eg consider this dependency chain:
get >> branch >> [ create, update ]>> join >> execute
The 'execute' task might need to know whether the 'branch' decided to create a
new thing to run, or whether to use the existing one from the 'get'. Without an
XCOM push from the branch return value, it is difficult to pick up the correct
value later on.
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