Question

I want to make each of the time stamps on my ruby application according to the user selected time zone. I am new to ruby in rails so can’t figure out how to do it.

I made drop down list appear for the user to select timezone from through

<%= time_zone_select( "user", 'time_zone', ActiveSupport::TimeZone.all, :default => "Beijing")%>

How to make the choice of time zone reflect on all the time stamps used.

Answer 1

using a before_filter in application_controller.rb makes sure that this method is called every request. The default timezone on every request is set by config.time_zone so you have to update Time.zone on every request. look at http://api.rubyonrails.org/classes/Time.html

before_filter :set_user_timezone

def set_user_timezone
  if current_user && current_user.time_zone.present?
    Time.zone = current_user.time_zone
  end
end

to evaluate an expression using a particular timezone, use Time.use_zone

Time.use_zone('Singapore') do
  Time.zone.parse(...) # returns a time in Singapore
end

UPDATE: using session to save the timezone

# application_controller.rb
before_filter :set_user_timezone

def set_user_timezone
  Time.zone = session[:timezone] || 'Default timezone here'
end

# time_zone_controller.rb
def save_time_zone
  session[:timezone] = params[:timezone]
end

# routes
match 'save_time_zone' => 'time_zone#save_time_zone'

# js
$('#user_time_zone').change(function() {
  $.ajax({
    url: '/save_time_zone',
    data: { time_zone: $(this).val() }
  })
})