Parse time in time zone in Rails

time_in_time_zone.rb

# parse date/time in detected time zone
time_zone_name    = params[:time_zone]
time_zone         = ActiveSupport::TimeZone.new(time_zone_name || Time.zone.name)
time_string       = "#{params[:date]} #{params[:time]}"
time_in_time_zone = time_zone.parse time_string