SQLAlchemy：在内部和数据库格式之间来回转换列值

SQLAlchemy：在内部和数据库格式之间来回转换列值

使用类型修饰符处理与自定义格式之间的转换。而不是

String

在定义列时使用此类型。

class MyTime(TypeDecorator):    impl = String    def __init__(self, length=None, format='%H:%M:%S', **kwargs)        super().__init__(length, **kwargs)        self.format = format    def process_literal_param(self, value, dialect):        # allow passing string or time to column        if isinstance(value, basestring):  # use str instead on py3 value = datetime.strptime(value, self.format).time()        # convert python time to sql string        return value.strftime(self.format) if value is not None else None    process_bind_param = process_literal_param    def process_result_value(self, value, dialect):        # convert sql string to python time        return datetime.strptime(value, self.format).time() if value is not None else None# in your modelclass MyModel(base):    time = Column(MyTime(length=7))