ashb commented on a change in pull request #8805:
URL: https://github.com/apache/airflow/pull/8805#discussion_r425008181
##########
File path: airflow/models/baseoperator.py
##########
@@ -634,6 +650,43 @@ def deps(self) -> Set[BaseTIDep]:
NotPreviouslySkippedDep(),
}
+ def _set_xcomargs_dependencies(self) -> None:
+ """
+ Resolves upstream dependencies of a task. In this way passing an
``XComArg``
+ as value for a template field will result in creating upstream
relation between
+ two tasks.
+
+ **Example**: ::
+
+ with DAG(...):
+ generate_content =
GenerateContentOperator(task_id="generate_content")
+ send_email = EmailOperator(...,
html_content=generate_content.output)
+
+ # This is equivalent to
+ with DAG(...):
+ generate_content =
GenerateContentOperator(task_id="generate_content")
+ send_email = EmailOperator(
+ ..., html_content="{{
task_instance.xcom_pull('generate_content') }}"
+ )
+ generate_content >> send_email
+
+ """
+ from airflow.models.xcom_arg import XComArg
+
+ def apply_set_upstream(arg: Any):
+ if isinstance(arg, XComArg):
+ self.set_upstream(arg.operator)
+ elif isinstance(arg, (tuple, set, list)):
+ for elem in arg:
+ apply_set_upstream(elem)
+ elif isinstance(arg, dict):
Review comment:
https://github.com/apache/airflow/commit/d567f9ab8d5fdd6d18509fd8d623b26795eca25c
Example of such a class from the docs/changelog:
```python
class MyDataReader:
template_fields = ['path']
def __init__(self, my_path):
self.path = my_path
# [additional code here...]
t = PythonOperator(
task_id='transform_data',
python_callable=transform_data
op_args=[
MyDataReader('/tmp/{{ ds }}/my_file')
],
dag=dag)
```
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