Make Rails ignore daylight saving time when displaying a date

问题

I have a date stored in UTC in my Rails app and am trying to display it to a user who has "Eastern Time (US & Canada)" as their timezone. The problem is that rails keeps converting it to Eastern Daylight Time (EDT) so midnight is being displayed as 8am when it should be 7am. Is there anyway to prevent the DST conversion?

>> time = DateTime.parse("2013-08-26T00:00:00Z")
=> Mon, 26 Aug 2013 00:00:00 +0000 
>> time.in_time_zone("Eastern Time (US & Canada)")
=> Sun, 25 Aug 2013 20:00:00 EDT -04:00

Update

I eventually went with a twist on @zeantsoi 's approach. I'm not a huge fan of adding too many rails helpers so I extended active support's TimeWithZone class.

class ActiveSupport::TimeWithZone
  def no_dst
    if self.dst?
      self - 1.hour
    else
      self
    end
  end
end

Now I can do time.in_time_zone("Eastern Time (US & Canada)").no_dst

回答1:

Create a helper that utilizes the dst? method on TimeZone to check whether the passed timezone is currently in DST. If it is, then subtract an hour from the supplied DateTime instance:

# helper function
module TimeConversion
  def no_dst(datetime, timezone)
    Time.zone = timezone

    if Time.zone.now.dst?
        return datetime - 1.hour
    end

    return datetime
  end
end

Then, render the adjusted (or non-adjusted) time in your view:

# in your view
<%= no_dst(DateTime.parse("2013-08-26T00:00:00Z"), 'Eastern Time (US & Canada)') %>
#=> Sun, 25 Aug 2013 19:00:00 EDT -04:00

来源：https://stackoverflow.com/questions/18541571/make-rails-ignore-daylight-saving-time-when-displaying-a-date

标签

ruby-on-rails

ruby

datetime

dst