Ruby-on-rails DateTime.now 还是 Time.now？
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DateTime.now or Time.now?
提问by Zabba
Which of the two should I be using in my Rails application:
我应该在我的 Rails 应用程序中使用这两个中的哪一个：
DateTime.now or Time.now
Is there any harm in using both in the application?
在应用程序中同时使用两者有什么危害吗？
Can there ever be any differences between the two in case of the above (now) example? (On my current system they are both showing the same time)
在上述 ( now) 示例的情况下，两者之间是否有任何区别？（在我当前的系统上，它们都显示在同一时间）
采纳答案by slandau
In reference to Time.now(not DateTime.now):
关于Time.now（不是DateTime.now）：
The object created will be created using the resolution available on your system clock, and so may include fractional seconds.
创建的对象将使用系统时钟上可用的分辨率创建，因此可能包含小数秒。
a = Time.new #=> Wed Apr 09 08:56:03 CDT 2003
b = Time.new #=> Wed Apr 09 08:56:03 CDT 2003
a == b #=> false
"%.6f" % a.to_f #=> "1049896563.230740"
"%.6f" % b.to_f #=> "1049896563.231466"
回答by Yarin
Use (Date)Time.currentinstead of (Date)Time.now
使用(Date)Time.current代替 (Date)Time.now
Rails extends the Timeand DateTimeobjects, and includes the currentproperty for retrieving the time the Rails environment is set to (default = UTC), as opposed to the server time (Could be anything).
Rails 扩展了Time和DateTime对象，并包括current用于检索 Rails 环境设置的时间（默认 = UTC）而不是服务器时间（可以是任何东西）的属性。
This is critical- You should always be working in UTC time except when converting between timezones for user input or display- but many production systems are notUTC by default. (e.g. Heroku is set to PST (GMT -8))
这是至关重要的 - 您应该始终在 UTC 时间工作，除非在时区之间转换以进行用户输入或显示 - 但许多生产系统默认情况下不是UTC。（例如 Heroku 设置为 PST (GMT -8)）
See article here
看这里的文章
回答by KurtPreston
If you want to get the time in the application's time zone, you'll need to call Time.zone.now, so that's what I generally use.
如果要获取应用程序时区的时间，则需要调用Time.zone.now，这就是我通常使用的方法。
Time.nowand DateTime.nowwill both return a time in the system's time, which often is set to UTC.
Time.now并且DateTime.now都将返回系统时间中的时间，通常设置为 UTC。
