数字小数被忽略并且变量是浮点类型

Question

Using SQLAlchemy 1.3.5, Postgres 9.6, and Python 3.6.8 a field on a model is defined as Decimal via price = Column(Numeric(asdecimal=True)) however printing out the model's type shows its a float:

subscription.price
2.5
(Pdb) type(subscription.price)
<class 'float'>

如何让 SQLAlchemy 使用Decimal类型？

该文档甚至说指定asdecimal是不必要的，因为它是默认值：

    This type returns Python ``decimal.Decimal`` objects by default, unless
    the :paramref:`.Numeric.asdecimal` flag is set to False, in which case
    they are coerced to Python ``float`` objects.