猜测Python中的日期格式

Question

我正在写一个Python模块里的方法，目的是为了让用户的生活更轻松。这个方法实现了在日历中创建事件的功能。

def update_event(start_datetime=None, end_datetime=None, description=None):
'''
Args:
  start_date: string datetime in the format YYYY-MM-DD or in RFC 3339
  end_date: string datetime in the format YYYY-MM-DD or in RFC 3339
  description: string with description (\n are transforrmed into new lines)
'''

如果用户指定了开始日期或结束日期，就需要检查一下，看看这个日期是按照YYYY-MM-DD格式写的，还是按照datetime RFC 3339格式写的。

if (start_date is not None):
    # Check whether we have an date or datetime value
    # Whole day events are represented as YYYY-MM-DD
    # Other events are represented as 2014-04-25T10:47:00.000-07:00
    whole_day_event = False
    try:
        new_start_time = datetime.datetime.strptime(start_date,'YYYY-MM-DD')
        # Here the event date is updated
        try:
            new_start_time = datetime.datetime.strptime(start_date,'%Y-%m-%dT%H:%M:%S%z')
            #Here the event date is updated
        except ValueError:
            return (ErrorCodeWhatever)
    except ValueError:
        return (ErrorCodeWhatever)

这样做是否合适？有没有更好的方法来检查我收到的日期类型呢？谢谢！

Answer 1

在扩展@Ffisegydd的回答时，你还可以指定你想要的目标日期时间格式，像这样：

from dateutil.parser import parse

def update_event(start_datetime=None, end_datetime=None, description=None):
    if start_datetime is not None:
        new_start_time = parse(start_datetime)

        return new_start_time

d = ['06/07/2021 06:40:23.277000','06/07/2021 06:40','06/07/2021']

new = [update_event(i) for i in d]

for date in new:
    print(date.strftime('%Y/%m/%d %H:%M:%S.%f'))

Answer 2

dateutil.parser.parse 可以用来尝试把字符串转换成 datetime 对象。

from dateutil.parser import parse

def update_event(start_datetime=None, end_datetime=None, description=None):
    if start_datetime is not None:
        new_start_time = parse(start_datetime)

        return new_start_time

d = ['23/04/2014', '24-04-2013', '25th April 2014']

new = [update_event(i) for i in d]

for date in new:
    print(date)
    # 2014-04-23 00:00:00
    # 2013-04-24 00:00:00
    # 2014-04-25 00:00:00