ruby-on-rails - 日期时间到时间转换中奇怪的 Ruby 行为

Question

我的目标是从 DateTime 实例获取 Time 实例

这之前已经在这里讨论过，但我仍然很困惑:Convert to/from DateTime and Time in Ruby

对我来说，在运行 ruby​​ 1.9.3p0(2011-10-30 修订版 33570)[x86_64-darwin11.2.0] 的 irb 中，一切正常

1.9.3p0 :001 > require 'Date'
 => true 
1.9.3p0 :002 > require 'Time'
 => true 
1.9.3p0 :003 > t=DateTime.now
 => #<DateTime: 2012-07-01T01:57:32+05:30 ((2456109j,73652s,621060000n),+19800s,2299161j)> 
1.9.3p0 :004 > t2=t.to_time
 => 2012-07-01 01:57:32 +0530 
1.9.3p0 :005 > t.class
 => DateTime 
1.9.3p0 :006 > t2.class
 => Time 
1.9.3p0 :007 > 

然而，当在同一个 ruby​​ 平台上使用 rails console v 3.2.3 时

1.9.3p0 :001 > t=DateTime.now
 => Sun, 01 Jul 2012 02:00:00 +0530 
1.9.3p0 :002 > t.class
 => DateTime 
1.9.3p0 :003 > t2=t.to_time
 => Sun, 01 Jul 2012 02:00:00 +0530
1.9.3p0  > t2.class
 => DateTime

如何从 Rails 中的 DateTime 获取时间实例？

Answer 1

根据Rails documentation for DateTime.to_time() ,

If self has an offset other than 0, self will just be returned unaltered

要更改为 0 偏移量，请使用 DateTime.utc() .

1.9.3p194 :005 > t3=t2.utc
 => Sat, 30 Jun 2012 20:43:21 +0000 
1.9.3p194 :006 > t3.offset
 => (0/1) 
1.9.3p194 :007 > t4=t3.to_time
 => 2012-06-30 20:43:21 UTC 
1.9.3p194 :008 > t4.class
 => Time