use_zone

Allows override of Time.zone locally inside supplied block; resets Time.zone to existing value when done.

 class ApplicationController < ActionController::Base
   around_action :set_time_zone

   private

   def set_time_zone
     Time.use_zone(current_user.timezone) { yield }
   end
 end

NOTE: This won't affect any <tt>ActiveSupport::TimeWithZone</tt>
objects that have already been created, e.g. any model timestamp
attributes that have been read before the block will remain in
the application's default timezone.