python/pytz从本地时区转换为UTC然后返回的问题 [英] Issue with python/pytz Converting from local timezone to UTC then back

问题描述

我需要将日期从本地时间戳转换为 UTC，然后再转换回本地时间戳.

I have a requirement to convert a date from a local time stamp to UTC then back to the local time stamp.

奇怪的是，当从 UTC 转换回本地时，python 决定它是 PDT 而不是原始 PST，因此转换后的日期增加了一个小时.有人可以向我解释发生了什么或我做错了什么吗?

Strangely, when converting back to the local from UTC python decides it is PDT instead of the original PST so the post converted date has gained an hour. Can someone explain to me what is going on or what I am doing wrong?

from datetime import datetime
from pytz import timezone
import pytz

DATE_FORMAT = '%Y-%m-%d %H:%M:%S %Z%z'

def print_formatted(dt):
    formatted_date = dt.strftime(DATE_FORMAT)
    print "%s :: %s" % (dt.tzinfo, formatted_date)


#convert the strings to date/time
date = datetime.now()
print_formatted(date)

#get the user's timezone from the pofile table
users_timezone = timezone("US/Pacific")

#set the parsed date's timezone
date = date.replace(tzinfo=users_timezone)
date = date.astimezone(users_timezone)
print_formatted(date)

#Create a UTC timezone
utc_timezone = timezone('UTC')
date = date.astimezone(utc_timezone)
print_formatted(date)

#Convert it back to the user's local timezone
date = date.astimezone(users_timezone)
print_formatted(date)

这是输出:

None :: 2011-09-18 18:24:23 
US/Pacific :: 2011-09-18 18:24:23 PST-0800
UTC :: 2011-09-19 02:24:23 UTC+0000
US/Pacific :: 2011-09-18 19:24:23 PDT-0700

推荐答案

更改

date = date.replace(tzinfo=users_timezone)

到

date = users_timezone.localize(date)

localize 针对夏令时进行调整，replace 不会.有关详细信息，请参阅文档.

localize adjusts for Daylight Savings Time, replace does not. See the docs for more info.

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