pytz 本地化与日期时间替换

2022-01-16 00:00:00 python datetime timezone pytz utc

问题描述

我在使用 pytz 的 .localize() 函数时遇到了一些奇怪的问题.有时它不会对本地化的日期时间进行调整:

I'm having some weird issues with pytz's .localize() function. Sometimes it wouldn't make adjustments to the localized datetime:

.localize 行为:

.localize behaviour:

>>> tz
<DstTzInfo 'Africa/Abidjan' LMT-1 day, 23:44:00 STD> 
>>> d
datetime.datetime(2009, 9, 2, 14, 45, 42, 91421)

>>> tz.localize(d)
datetime.datetime(2009, 9, 2, 14, 45, 42, 91421, 
                  tzinfo=<DstTzInfo 'Africa/Abidjan' GMT0:00:00 STD>)
>>> tz.normalize(tz.localize(d))
datetime.datetime(2009, 9, 2, 14, 45, 42, 91421,
                  tzinfo=<DstTzInfo 'Africa/Abidjan' GMT0:00:00 STD>)

如您所见，本地化/规范化操作并未改变时间.但是，如果使用 .replace:

As you can see, time has not been changed as a result of localize/normalize operations. However, if .replace is used:

>>> d.replace(tzinfo=tz)
datetime.datetime(2009, 9, 2, 14, 45, 42, 91421, 
                  tzinfo=<DstTzInfo 'Africa/Abidjan' LMT-1 day, 23:44:00 STD>)
>>> tz.normalize(d.replace(tzinfo=tz))
datetime.datetime(2009, 9, 2, 15, 1, 42, 91421,
                  tzinfo=<DstTzInfo 'Africa/Abidjan' GMT0:00:00 STD>)

这似乎对日期时间进行了调整.

Which seems to make adjustments into datetime.

问题是 - 哪个是正确的，为什么其他人是错的?

Question is - which is correct and why other's wrong?

解决方案

localize 只是假设您传递给它的天真日期时间是正确的"(除了不知道时区！)等等只是设置时区，没有其他调整.

localize just assumes that the naive datetime you pass it is "right" (except for not knowing about the timezone!) and so just sets the timezone, no other adjustments.

您可以(并且建议...)在 UTC 内部工作(而不是使用简单的日期时间)并在需要以本地化方式执行日期时间的 I/O 时使用 replace(normalize 将处理 DST 等).

You can (and it's advisable...) internally work in UTC (rather than with naive datetimes) and use replace when you need to perform I/O of datetimes in a localized way (normalize will handle DST and the like).

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