Python sqlalchemy.func 模块，abs() 实例源码

def acquisitions_by_mapgrid_and_date(date, mapgrid_target, day_buffer):
    from sqlalchemy import Integer, func, Date
    from sqlalchemy.sql.expression import cast
    session = SESSION_MAKER()
    images_paths = session.query(RawProduct.product_path, RapidEyeFootPrintsMexicoOld.code, RapidEyeFootPrintsMexicoOld.mapgrid2).distinct().join(RawProduct.information).filter(RawProduct.satellite_id == 1, RapidEyeFootPrintsMexicoOld.mapgrid2 == mapgrid_target, cast(RapidEyeFootPrintsMexicoOld.code, Integer) == cast(Information.grid_id, Integer), func.abs(cast(RawProduct.acquisition_date, Date) - date) < day_buffer).all()
    #RawProduct.sensor_id
    return images_paths

def transferred_amount(from_account, to_account, begin_date=None, end_date=None):
    """
    Determine how much has been transferred from one account to another in a
    given interval.

    A negative value indicates that more has been transferred from to_account
    to from_account than the other way round.

    The interval boundaries may be None, which indicates no lower and upper
    bound respectively.
    :param FinanceAccount from_account:
    :param FinanceAccount to_account:
    :param date|None begin_date: since when (inclusive)
    :param date|None end_date: till when (inclusive)
    :rtype: int
    """
    split1 = aliased(Split)
    split2 = aliased(Split)
    query = session.session.query(
        cast(func.sum(
            sign(split2.amount) *
            least(func.abs(split1.amount), func.abs(split2.amount))
        ), Integer)
    ).select_from(
        split1
    ).join(
        (split2, split1.transaction_id == split2.transaction_id)
    ).join(
        Transaction, split2.transaction_id == Transaction.id
    ).filter(
        split1.account == from_account,
        split2.account == to_account,
        sign(split1.amount) != sign(split2.amount)
    )
    if begin_date is not None and end_date is not None:
        query = query.filter(
            between(Transaction.valid_date, begin_date, end_date)
        )
    elif begin_date is not None:
        query = query.filter(Transaction.valid_date >= begin_date)
    elif end_date is not None:
        query = query.filter(Transaction.valid_date <= end_date)
    return query.scalar()