ferruzzi commented on code in PR #50677:
URL: https://github.com/apache/airflow/pull/50677#discussion_r2110590988
##########
airflow-core/src/airflow/models/deadline.py:
##########
@@ -186,3 +159,52 @@ def serialize_deadline_alert(self):
"callback_kwargs": self.callback_kwargs,
}
)
+
+
+@provide_session
+def _fetch_from_db(model_reference: Column, session=None, **conditions) ->
datetime:
+ """
+ Fetch a datetime value from the database using the provided model
reference and filtering conditions.
+
+ For example, to fetch a TaskInstance's start_date:
+ _fetch_from_db(
+ TaskInstance.start_date, dag_id='example_dag',
task_id='example_task', run_id='example_run'
+ )
+
+ This generates SQL equivalent to:
+ SELECT start_date
+ FROM task_instance
+ WHERE dag_id = 'example_dag'
+ AND task_id = 'example_task'
+ AND run_id = 'example_run'
+
+ :param model_reference: SQLAlchemy Column to select (e.g.,
DagRun.logical_date, TaskInstance.start_date)
+ :param conditions: Filtering conditions applied as equality comparisons in
the WHERE clause.
+ Multiple conditions are combined with AND.
+ :param session: SQLAlchemy session (auto-provided by decorator)
+ """
+ query = select(model_reference)
+
+ for key, value in conditions.items():
+ query = query.where(getattr(model_reference.class_, key) == value)
+
+ compiled_query = query.compile(compile_kwargs={"literal_binds": True})
+ pretty_query = "\n ".join(str(compiled_query).splitlines())
+ logger.debug(
+ "Executing query:\n %r\nAs SQL:\n %s",
+ query,
+ pretty_query,
+ )
+
+ try:
+ result = session.scalar(query)
+ except SQLAlchemyError as e:
+ logger.error("Database query failed: (%s)", str(e))
Review Comment:
Is there a similar way to simplify the block below that which is currently:
```
if result is None:
message = f"No matching record found in the database for query:\n
{pretty_query}"
logger.error(message)
raise ValueError(message)
```
I always felt python needed a "log then raise" method, but maybe there has
been one all along?
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