1fanwang commented on code in PR #50677:
URL: https://github.com/apache/airflow/pull/50677#discussion_r2093560619
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airflow-core/src/airflow/models/deadline.py:
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@@ -123,7 +122,71 @@ class DeadlineReference(Enum):
dag.deadline.reference.evaluate_with(dag_id=dag.dag_id)
"""
+ # Available References.
+ #
+ # The value is the name of the method executed to fetch the datetime
+ # value for the given Reference. For example DAGRUN_LOGICAL_DATE =
"dagrun_logical_date"
+ # will execute dagrun_logical_date() to find the dagrun's logical date.
DAGRUN_LOGICAL_DATE = "dagrun_logical_date"
+ DAGRUN_QUEUED_AT = "dagrun_queued_at"
+ _CUSTOM_REFERENCE_BASE = "_custom_reference"
+
+ def __init__(self, value):
+ self._fixed_dt = None # Initialize the storage for fixed datetime
+ super().__init__()
+
+ @classmethod
+ def FIXED_DATETIME(cls, dt: datetime):
+ """
+ Calculate a reference based on a set datetime rather than fetching a
value from the database.
+
+ For example, you could set the Deadline for "tomorrow before 9AM" by
+ providing the appropriate datetime object."
+ """
+ instance = object.__new__(cls)
+ instance._value_ = "fixed_datetime"
+ instance._fixed_dt = dt
+ return instance
+
+ def evaluate_with(self, **kwargs):
+ """Call the method in the enum's value with the provided kwargs."""
+ if self._fixed_dt:
+ return self._fixed_dt
+ return getattr(self, self.value)(**kwargs)
+
+ def evaluate(self):
+ """Call evaluate_with() without any conditions, because it looks
strange in use that way."""
+ return self.evaluate_with()
+
+ @provide_session
+ def _fetch_from_db(self, model_class: Base, column: str, session=None,
**conditions) -> datetime:
+ """
+ Fetch a datetime stored in the database.
+
+ :param model_class: The Airflow model class (e.g., DagRun,
TaskInstance, etc.)
+ :param column: The column name to fetch
+ :param session: SQLAlchemy session (provided by decorator)
+
+ :param conditions: Key-value pairs which are passed to the WHERE clause
+ """
+ query = select(getattr(model_class, column))
+
+ for key, value in conditions.items():
+ query = query.where(getattr(model_class, key) == value)
+ # This should build a query similar to:
+ # session.scalar(select(DagRun.logical_date).where(DagRun.dag_id ==
dag_id))
+ self.log.debug("db query: session.scalar(%s)", query)
+ return session.scalar(query)
Review Comment:
What's the intended behavior if no matching records found
do we need to handle existence / check if None here?
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