在SQLAlchemy和SQLite后端中使用日期时间限制

Question

我正在尝试使用SQL alchemy的按日期的查询限制。示例代码如下：

def young_puppies(session=get_session()):
    """Query all of the puppies.

    Return those that are less than 6 months old organized by
    the youngest first.
    """
    young = []
    today = datetime.date.today()
    sixm = today - relativedelta(months=-6)
    sel = session.query(Puppy).\
        filter(Puppy.dateOfBirth.between(sixm, today)).\
        order_by(desc(Puppy.dateOfBirth))
    print (sel)
    res = session.execute(sel)
    for row in res:
        young.append(dict(row))
    session.close
    return young

但是，查询生成出现意外行为：

SELECT puppy.name AS puppy_name, puppy.id AS puppy_id, puppy."dateOfBirth" AS "puppy_dateOfBirth", puppy.gender AS puppy_gender, puppy.picture AS puppy_picture, puppy.weight AS puppy_weight, puppy.shelter_id AS puppy_shelter_id 
FROM puppy 
WHERE puppy."dateOfBirth" BETWEEN ? AND ? ORDER BY puppy."dateOfBirth" DESC

即使在插入过滤器之前将类型强制转换为str，也会显示相同的行为。我不知道为什么会发生这种情况，或者是否有解决办法。根据我所做的研究，这应该行得通。这个？而不是限制的日期。你知道吗

编辑：

奇怪的是，我在第六个月的约会上做了一个刺痛的动作：

def young_puppies(session=get_session()):
    """Query all of the puppies.

    Return those that are less than 6 months old organized by
    the youngest first.
    """
    young = []
    tday = datetime.date.today()
    sixm = tday - relativedelta(months=-6)
    sel = session.query(Puppy).\
        filter(Puppy.dateOfBirth.
               between(sixm.strftime('%y-%m-%d'), tday)).\
        order_by(desc(Puppy.dateOfBirth))
    print (sel)
    res = session.execute(sel)
    for row in res:
        young.append(dict(row))
    session.close
    return young