airflow/operators/weekday.py

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from typing import Dict, Iterable, Union

from airflow.operators.branch import BaseBranchOperator
from airflow.utils import timezone
from airflow.utils.weekday import WeekDay


class BranchDayOfWeekOperator(BaseBranchOperator):
    """
    Branches into one of two lists of tasks depending on the current day.
    For more information on how to use this operator, take a look at the guide:
    :ref:`howto/operator:BranchDayOfWeekOperator`

    :param follow_task_ids_if_true: task id or task ids to follow if criteria met
    :type follow_task_ids_if_true: str or list[str]
    :param follow_task_ids_if_false: task id or task ids to follow if criteria does not met
    :type follow_task_ids_if_false: str or list[str]
    :param week_day: Day of the week to check (full name). Optionally, a set
        of days can also be provided using a set.
        Example values:

            * ``"MONDAY"``,
            * ``{"Saturday", "Sunday"}``
            * ``{WeekDay.TUESDAY}``
            * ``{WeekDay.SATURDAY, WeekDay.SUNDAY}``

    :type week_day: set or str or airflow.utils.weekday.WeekDay
    :param use_task_execution_day: If ``True``, uses task's execution day to compare
        with is_today. Execution Date is Useful for backfilling.
        If ``False``, uses system's day of the week.
    :type use_task_execution_day: bool
    """

    def __init__(
        self,
        *,
        follow_task_ids_if_true: Union[str, Iterable[str]],
        follow_task_ids_if_false: Union[str, Iterable[str]],
        week_day: Union[str, Iterable[str]],
        use_task_execution_day: bool = False,
        **kwargs,
    ) -> None:
        super().__init__(**kwargs)
        self.follow_task_ids_if_true = follow_task_ids_if_true
        self.follow_task_ids_if_false = follow_task_ids_if_false
        self.week_day = week_day
        self.use_task_execution_day = use_task_execution_day
        self._week_day_num = None

        if isinstance(self.week_day, str):
            self._week_day_num = {WeekDay.get_weekday_number(week_day_str=self.week_day)}
        elif isinstance(self.week_day, WeekDay):
            self._week_day_num = {self.week_day}
        elif isinstance(self.week_day, set):
            if all(isinstance(day, str) for day in self.week_day):
                self._week_day_num = {WeekDay.get_weekday_number(day) for day in week_day}
            elif all(isinstance(day, WeekDay) for day in self.week_day):
                self._week_day_num = self.week_day
        else:
            raise TypeError(
                'Unsupported Type for week_day parameter: {}. It should be one of str'
                ', set or Weekday enum type'.format(type(week_day))
            )

    def choose_branch(self, context: Dict) -> Union[str, Iterable[str]]:
        if self.use_task_execution_day:
            now = context["execution_date"]
        else:
            now = timezone.make_naive(timezone.utcnow(), self.dag.timezone)

        if now.isoweekday() in self._week_day_num:
            return self.follow_task_ids_if_true
        return self.follow_task_ids_if_false