Rails ActiveSupport时间解析? [英] Rails ActiveSupport Time Parsing?
问题描述
Rails的ActiveSupport模块将内置的ruby Time类扩展为许多方法.
值得注意的是，有一种to_formatted_s方法，它使您可以编写Time.now.to_formatted_s(:db)来获取数据库格式的字符串，而不必到处都编写难看的strftime格式字符串.
Notably, there is the to_formatted_s method, which lets you write Time.now.to_formatted_s(:db) to get a string in Database format, rather than having to write ugly strftime format-strings everywhere.
我的问题是，有没有办法倒退?
My question is, is there a way to go backwards?
类似于Time.parse_formatted_s(:db)的东西，它将解析数据库格式的字符串，并返回一个新的Time对象.这似乎是Rails应该提供的东西，但是如果是的话，我找不到它.
Something like Time.parse_formatted_s(:db) which would parse a string in Database format, returning a new Time object. This seems like something that rails should be providing, but if it is, I can't find it.
我只是找不到它，还是需要自己编写?
Am I just not able to find it, or do I need to write it myself?
谢谢
推荐答案
毕竟，ActiveSupport确实提供了您正在寻找的解析方法(我也正在寻找)！ —至少如果您要解析的字符串是标准的，ISO-8601格式(:db格式)的日期.
It looks like ActiveSupport does provide the parsing methods you are looking for (and I was looking for too), after all! — at least if the string you are trying to parse is a standard, ISO-8601-formatted (:db format) date.
如果您要解析的日期已经在您的本地时区中，那真的很简单！
If the date you're trying to parse is already in your local time zone, it's really easy!
> Time.zone.parse('2009-09-24 08:28:43')
=> Thu, 24 Sep 2009 08:28:43 PDT -07:00
> Time.zone.parse('2009-09-24 08:28:43').class
=> ActiveSupport::TimeWithZone
然后可以将知道时区的时间轻松转换为UTC
and that time-zone-aware time can then easily be converted to UTC
> Time.zone.parse('2009-09-24 08:28:43').utc
=> 2009-09-24 15:28:43 UTC
或其他时区:
> ActiveSupport::TimeZone.us_zones.map(&:name)
=> ["Hawaii", "Alaska", "Pacific Time (US & Canada)", "Arizona", "Mountain Time (US & Canada)", "Central Time (US & Canada)", "Eastern Time (US & Canada)", "Indiana (East)"]
> Time.zone.parse('2009-09-24 08:28:43').utc.in_time_zone('Eastern Time (US & Canada)')
=> Thu, 24 Sep 2009 11:28:43 EDT -04:00
另一方面，如果您要解析的日期字符串使用UTC，则似乎没有任何方法可以将直接解析为TimeWithZone，但是我能够要解决此问题，请先使用DateTime.strptime ...
If the date string you're trying to parse is in UTC, on the other hand, it doesn't look like there's any method to parse it directly into a TimeWithZone, but I was able to work around that be first using DateTime.strptime...
如果您要解析的日期是UTC，并且希望保留为UTC，则可以使用:
If the date you're trying to parse is in UTC and you want it to stay as UTC, you can use:
> DateTime.strptime('2009-09-24 08:28:43', '%Y-%m-%d %H:%M:%S').to_time
=> 2009-09-24 08:28:43 UTC
如果您要解析的日期是UTC，并且希望将其转换为默认时区，则可以使用:
If the date you're trying to parse is in UTC and you want it converted to your default time zone, you can use:
> DateTime.strptime('2009-09-24 08:28:43', '%Y-%m-%d %H:%M:%S').to_time.in_time_zone
=> Thu, 24 Sep 2009 01:28:43 PDT -07:00
看起来它甚至可以解析其他格式，例如Time#to_s生成的奇怪格式:
It looks like it can even parse other formats, such as the strange format that Time#to_s produces:
irb -> Time.zone.parse('Wed, 23 Sep 2009 02:18:08').to_s(:db)
=> "2009-09-23 09:18:08"
irb -> Time.zone.parse('Wed, 23 Sep 2009 02:18:08 EDT').to_s(:db)
=> "2009-09-23 06:18:08"
我很感动.
以下是[ http://api.rubyonrails中的其他示例.org/classes/ActiveSupport/TimeWithZone.html] [1] :
Time.zone = 'Eastern Time (US & Canada)' # => 'Eastern Time (US & Canada)'
Time.zone.local(2007, 2, 10, 15, 30, 45) # => Sat, 10 Feb 2007 15:30:45 EST -05:00
Time.zone.parse('2007-02-10 15:30:45') # => Sat, 10 Feb 2007 15:30:45 EST -05:00
Time.zone.at(1170361845) # => Sat, 10 Feb 2007 15:30:45 EST -05:00
Time.zone.now # => Sun, 18 May 2008 13:07:55 EDT -04:00
Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone # => Sat, 10 Feb 2007 15:30:45 EST -05:00
更多文档链接供参考:
- http://api.rubyonrails.org/classes/ActiveSupport/TimeWithZone.html
- http://api.rubyonrails.org/classes/ActiveSupport/TimeZone.html
- http://api.rubyonrails.org/classes/ActiveSupport/TimeWithZone.html
- http://api.rubyonrails.org/classes/ActiveSupport/TimeZone.html
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