model.py 文件源码

def get_current_station_info(cls, dbsession):
        """as the method name suggests this returns the up to date station information."""
        sub = dbsession.query(UsageData.station_id, func.max(UsageData.id).label('max_update')).group_by(
            UsageData.station_id).subquery()
        return dbsession.query(
            UsageData.last_update,
             UsageData.available_bike_stands, UsageData.available_bikes).join(sub, and_(
                sub.c.max_update == UsageData.id)).all()