airflow/models/dagrun.py
def get_previous_scheduled_dagrun(self, session=None):
        """The previous, SCHEDULED DagRun, if there is one"""
        dag = self.get_dag()

        return session.query(DagRun).filter(
            DagRun.dag_id == self.dag_id,
            DagRun.execution_date == dag.previous_schedule(self.execution_date)
        ).first()
def get_previous_scheduled_dagrun(self, session=None):
        """The previous, SCHEDULED DagRun, if there is one"""
        dag = self.get_dag()

        return session.query(DagRun).filter(
            DagRun.dag_id == self.dag_id,
            DagRun.execution_date == dag.previous_schedule(self.execution_date)
        ).first()
The previous, SCHEDULED DagRun, if there is one