[GitHub] [airflow] ephraimbuddy commented on pull request #16823: Add ability to specify XCom key for operators and task decorator

[GitBox <gi...@apache.org>]

ephraimbuddy commented on pull request #16823:
URL: https://github.com/apache/airflow/pull/16823#issuecomment-896697397


   @ashb, I have just discovered that XCom key can actually be changed with the TaskFlow API currently:
   
   ```python
   
   from airflow import DAG
   from airflow.utils.dates import days_ago
   
   value_1 = [1, 2, 3]
   value_2 = {'a': 'b'}
   
   dag = DAG(
       'example_xcom',
       schedule_interval="@once",
       start_date=days_ago(2),
       tags=['example'],
   )
   
   @dag.task()
   def push(**kwargs):
       """Pushes an XCom without a specific target"""
       kwargs['ti'].xcom_push(key='value from pusher 1', value=value_1)
   
   
   @dag.task()
   def push_by_returning():
       """Pushes an XCom without a specific target, just by returning it"""
       return value_2
   
   
   @dag.task()
   def puller(data1, data2, **kwargs):
       """Pull all previously pushed XComs and check if the pushed values match the pulled values."""
       ti = kwargs['ti']
       # get value_1
       pulled_value_1 = ti.xcom_pull(key=None, task_ids='push')
       if pulled_value_1 != value_1:
           raise ValueError(f'The two values differ {pulled_value_1} and {value_1}')
   
       # get value_2
       pulled_value_2 = data2
       if pulled_value_2 != value_2:
           raise ValueError(f'The two values differ {pulled_value_2} and {value_2}')
   
       # get both value_1 and value_2
       pulled_value_1, pulled_value_2 = ti.xcom_pull(key=None, task_ids=['push', 'push_by_returning'])
       if pulled_value_1 != value_1:
           raise ValueError(f'The two values differ {pulled_value_1} and {value_1}')
       if pulled_value_2 != value_2:
           raise ValueError(f'The two values differ {pulled_value_2} and {value_2}')
   
   
   puller(push(), push_by_returning())
   
   ```
   The decorated function accepts the `**kwargs` and we can use `ti.xcom_push` and also `ti.xcom_pull` 
   
   Closing this PR!


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