Time zone select rails helper with formatted offset

_localization.html.erb

<%= f.time_zone_select :time_zone, TimeZoneWithFormattedOffset.all.sort_by { |tz| [tz.now.utc_offset, tz.name] } %>

time_zone_with_formatted_offset.rb

class TimeZoneWithFormattedOffset < ActiveSupport::TimeZone
  def to_s
    "(GMT#{self.now.formatted_offset}) #{self.name}"
  end
end

I get this
NoMethodError (undefined method `[]' for nil:NilClass)` on `ruby-2.5.0/gems/activesupport-4.2.10/lib/active_support/values/time_zone.rb:243:in `[]'
when trying to use TimeZoneWithFormattedOffset.all. Maybe things have changed a lot since.

For whoever tries to use this, this works very well! After spending hours of debugging I noticed I had to add this to the custom class:

class TimeZoneWithFormattedOffset < ActiveSupport::TimeZone
  @lazy_zones_map = ThreadSafe::Cache.new

  def to_s
    "(GMT#{self.now.formatted_offset}) #{self.name}"
  end
end

Don't know why @lazy_zones_map wasn't instantiated which generated an exception when running all -> zones_map

@dduqueti, thanks a ton man, spent hours in debugging the same issue and wasn't able to figure out why the @lazy_zones_map is empty and throwing errors.