@classmethod
    @provide_session
    def get_one(
            cls,
            execution_date,
            key=None,
            task_id=None,
            dag_id=None,
            include_prior_dates=False,
            session=None):
        filters = []
        if key:
            filters.append(cls.key == key)
        if task_id:
            filters.append(cls.task_id == task_id)
        if dag_id:
            filters.append(cls.dag_id == dag_id)
        if include_prior_dates:
            filters.append(cls.execution_date <= execution_date)
        else:
            filters.append(cls.execution_date == execution_date)

        query = (
            session.query(cls.value)
            .filter(and_(*filters))
            .order_by(cls.execution_date.desc(), cls.timestamp.desc())
            .limit(1))

        result = query.first()
        if result:
            return result.value
Retrieve an XCom value, optionally meeting certain criteria
dataset/ETHPy150Open airbnb/airflow/airflow/models.py/XCom.get_one