[GitHub] Fokko closed pull request #4056: [AIRFLOW-3207] option to stop task pushing result to xcom

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

Fokko closed pull request #4056: [AIRFLOW-3207] option to stop task pushing result to xcom
URL: https://github.com/apache/airflow/pull/4056
 
 
   

This is a PR merged from a forked repository.
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diff --git a/airflow/models/__init__.py b/airflow/models/__init__.py
index aa93f5cb88..611ed99bc7 100755
--- a/airflow/models/__init__.py
+++ b/airflow/models/__init__.py
@@ -1431,7 +1431,7 @@ def signal_handler(signum, frame):
                     result = task_copy.execute(context=context)
 
                 # If the task returns a result, push an XCom containing it
-                if result is not None:
+                if task_copy.do_xcom_push and result is not None:
                     self.xcom_push(key=XCOM_RETURN_KEY, value=result)
 
                 task_copy.post_execute(context=context, result=result)
@@ -2231,6 +2231,9 @@ class derived from this one results in the creation of a task object,
             )
 
     :type executor_config: dict
+    :param do_xcom_push: if True, an XCom is pushed containing the Operator's
+        result
+    :type do_xcom_push: bool
     """
 
     # For derived classes to define which fields will get jinjaified
@@ -2285,6 +2288,7 @@ def __init__(
             run_as_user=None,
             task_concurrency=None,
             executor_config=None,
+            do_xcom_push=True,
             inlets=None,
             outlets=None,
             *args,
@@ -2369,6 +2373,7 @@ def __init__(
         self.run_as_user = run_as_user
         self.task_concurrency = task_concurrency
         self.executor_config = executor_config or {}
+        self.do_xcom_push = do_xcom_push
 
         # Private attributes
         self._upstream_task_ids = set()
@@ -2422,6 +2427,7 @@ def __init__(
             'on_failure_callback',
             'on_success_callback',
             'on_retry_callback',
+            'do_xcom_push',
         }
 
     def __eq__(self, other):
diff --git a/tests/models.py b/tests/models.py
index 2e8a139eb0..8ebf8720ce 100644
--- a/tests/models.py
+++ b/tests/models.py
@@ -2429,6 +2429,32 @@ def test_xcom_pull_different_execution_date(self):
                                       include_prior_dates=True),
                          value)
 
+    def test_xcom_push_flag(self):
+        """
+        Tests the option for Operators to push XComs
+        """
+        value = 'hello'
+        task_id = 'test_no_xcom_push'
+        dag = models.DAG(dag_id='test_xcom')
+
+        # nothing saved to XCom
+        task = PythonOperator(
+            task_id=task_id,
+            dag=dag,
+            python_callable=lambda: value,
+            do_xcom_push=False,
+            owner='airflow',
+            start_date=datetime.datetime(2017, 1, 1)
+        )
+        ti = TI(task=task, execution_date=datetime.datetime(2017, 1, 1))
+        ti.run()
+        self.assertEqual(
+            ti.xcom_pull(
+                task_ids=task_id, key=models.XCOM_RETURN_KEY
+            ),
+            None
+        )
+
     def test_post_execute_hook(self):
         """
         Test that post_execute hook is called with the Operator's result.


 

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