Python - 将UTC datetime字符串转换为本地datetime [英] Python - Convert UTC datetime string to local datetime

问题描述

我从来没有必要将时间转换成utc。最近有一个请求让我的应用程序成为时区知道，我一直在自己的圈子。许多关于将本地时间转换为utc的信息，我发现相当基本（也许我也在做错），但是我没有找到任何有关容易将utc时间转换为最终用户时区的信息。

简而言之，android应用程序发送我（appengine app）数据，在该数据中是一个时间戳。要将该时间戳存储到我正在使用的utc时间：

  datetime.utcfromtimestamp（timestamp）
  

这似乎正在工作。当我的应用程序存储数据时，它正在5小时存储（我是EST -5）

数据存储在appengine的BigTable中，并且在检索到它以这样的字符串出来：

 2011-01-21 02:37:21
  

如何在用户正确的时区将此字符串转换为DateTime？

此外，用户时区信息的推荐存储是什么？ （你通常如何存储tz信息，即：-5：00或EST等？）我确定我的第一个问题的答案可能包含第二个参数的答案。

解决方案

如果您不想提供自己的 tzinfo ，请查看 python-dateutil 库。它在 zoneinfo（Olson）数据库之上提供 tzinfo 实现以便您可以通过某种规范的名称来引用时区规则。

  from datetime import datetime 
 from dateutil import tz 
 
＃方法1：硬编码区：
 from_zone = tz.gettz（'UTC'）
 to_zone = tz.gettz（'America / New_York'）
 
＃方法2：自动检测区域：
 from_zone = tz.tzutc（）
 to_zone = tz.tzlocal（）
 
＃utc = datetime.utcnow ）
 utc = datetime.strptime（'2011-01-21 02:37:21'，'％Y-％m-％d％H：％M：％S'）
 
＃在
＃datetime对象为naive时默认为
 utc = utc.replace（tzinfo = from_zone）
 
＃转换日期时间对象时区
 central = utc.astimezone（to_zone）
  

修改展开示例以显示 strptime 用法

编辑2 修正API使用情况，以显示更好的入门点方法

编辑3 包含自动检测方法时区（Yarin）

I've never had to convert time to and from utc. Recently had a request to have my app be timezone aware, and I've been running myself in circles. Lots of information on converting local time to utc, which I found fairly elementary (maybe I'm doing that wrong as well), but I can not find any information on easily converting the utc time to the end-users timezone.

In a nutshell, and android app sends me (appengine app) data and within that data is a timestamp. To store that timestamp to utc time I am using:

datetime.utcfromtimestamp(timestamp)

That seems to be working. When my app stores the data, it is being store as 5 hours ahead (I am EST -5)

The data is being stored on appengine's BigTable, and when retrieved it comes out as a string like so:

"2011-01-21 02:37:21"

How do I convert this string to a DateTime in the users correct time zone?

Also, what is the recommended storage for a users timezone information? (How do you typically store tz info ie: "-5:00" or "EST" etc etc ?) I'm sure the answer to my first question might contain a parameter the answers the second.

解决方案

If you don't want to provide your own tzinfo objects, check out the python-dateutil library. It provides tzinfo implementations on top of a zoneinfo (Olson) database such that you can refer to time zone rules by a somewhat canonical name.

from datetime import datetime
from dateutil import tz

# METHOD 1: Hardcode zones:
from_zone = tz.gettz('UTC')
to_zone = tz.gettz('America/New_York')

# METHOD 2: Auto-detect zones:
from_zone = tz.tzutc()
to_zone = tz.tzlocal()

# utc = datetime.utcnow()
utc = datetime.strptime('2011-01-21 02:37:21', '%Y-%m-%d %H:%M:%S')

# Tell the datetime object that it's in UTC time zone since 
# datetime objects are 'naive' by default
utc = utc.replace(tzinfo=from_zone)

# Convert time zone
central = utc.astimezone(to_zone)

Edit Expanded example to show strptime usage

Edit 2 Fixed API usage to show better entry point method

Edit 3 Included auto-detect methods for timezones (Yarin)

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