Fokko closed pull request #4365: [AIRFLOW-1684] - Branching based on XCom variable (Docs) URL: https://github.com/apache/incubator-airflow/pull/4365
This is a PR merged from a forked repository. As GitHub hides the original diff on merge, it is displayed below for the sake of provenance: As this is a foreign pull request (from a fork), the diff is supplied below (as it won't show otherwise due to GitHub magic): diff --git a/docs/concepts.rst b/docs/concepts.rst index eac7a8a7f1..766b69b783 100644 --- a/docs/concepts.rst +++ b/docs/concepts.rst @@ -522,6 +522,37 @@ Not like this, where the join task is skipped .. image:: img/branch_bad.png +The ``BranchPythonOperator`` can also be used with XComs allowing branching +context to dynamically decide what branch to follow based on previous tasks. +For example: + +.. code:: python + + def branch_func(**kwargs): + ti = kwargs['ti'] + xcom_value = int(ti.xcom_pull(task_ids='start_task')) + if xcom_value >= 5: + return 'continue_task' + else: + return 'stop_task' + + start_op = BashOperator( + task_id='start_task', + bash_command="echo 5", + xcom_push=True, + dag=dag) + + branch_op = BranchPythonOperator( + task_id='branch_task', + provide_context=True, + python_callable=branch_func, + dag=dag) + + continue_op = DummyOperator(task_id='continue_task', dag=dag) + stop_op = DummyOperator(task_id='stop_task', dag=dag) + + start_op >> branch_op >> [continue_op, stop_op] + SubDAGs ======= ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
