Merge pull request #20625 from Envek/add_country_zones_method

Add ActiveSupport::TimeZone.country_zones helper

actionview/lib/action_view/helpers/form_options_helper.rb

@@ -268,10 +268,11 @@ def grouped_collection_select(object, method, collection, group_method, group_la
       # for more information.)
       #
       # You can also supply an array of ActiveSupport::TimeZone objects
-      # as +priority_zones+, so that they will be listed above the rest of the
-      # (long) list. (You can use ActiveSupport::TimeZone.us_zones as a convenience
-      # for obtaining a list of the US time zones, or a Regexp to select the zones
-      # of your choice)
+      # as +priority_zones+ so that they will be listed above the rest of the
+      # (long) list. You can use ActiveSupport::TimeZone.us_zones for a list
+      # of US time zones, ActiveSupport::TimeZone.country_zones(country_code)
+      # for another country's time zones, or a Regexp to select the zones of
+      # your choice.
       #
       # Finally, this method supports a <tt>:default</tt> option, which selects
       # a default ActiveSupport::TimeZone if the object's time zone is +nil+.

activesupport/CHANGELOG.md

+*   `ActiveSupport::TimeZone.country_zones(country_code)` looks up the
+    country's time zones by its two-letter ISO3166 country code, e.g.
+
+        >> ActiveSupport::TimeZone.country_zones(:jp).map(&:to_s)
+        => ["(GMT+09:00) Osaka"]
+
+        >> ActiveSupport::TimeZone.country_zones(:uy).map(&:to_s)
+        => ["(GMT-03:00) Montevideo"]
+
+    *Andrey Novikov*
+
 *   `Array#sum` compat with Ruby 2.4's native method.
 
     Ruby 2.4 introduces `Array#sum`, but it only supports numeric elements,

activesupport/lib/active_support/values/time_zone.rb

@@ -184,6 +184,7 @@ class TimeZone
     UTC_OFFSET_WITHOUT_COLON = UTC_OFFSET_WITH_COLON.tr(':', '')
 
     @lazy_zones_map = Concurrent::Map.new
+    @country_zones  = Concurrent::Map.new
 
     class << self
       # Assumes self represents an offset from UTC in seconds (as returned from
@@ -242,7 +243,18 @@ def [](arg)
       # A convenience method for returning a collection of TimeZone objects
       # for time zones in the USA.
       def us_zones
-        @us_zones ||= all.find_all { |z| z.name =~ /US|Arizona|Indiana|Hawaii|Alaska/ }
+        country_zones(:us)
+      end
+
+      # A convenience method for returning a collection of TimeZone objects
+      # for time zones in the country specified by its ISO 3166-1 Alpha2 code.
+      def country_zones(country_code)
+        code = country_code.to_s.upcase
+        @country_zones[code] ||=
+          TZInfo::Country.get(code).zone_identifiers.map do |tz_id|
+            name = MAPPING.key(tz_id)
+            name && self[name]
+          end.compact.sort!
       end
 
       private

activesupport/test/time_zone_test.rb

@@ -491,6 +491,11 @@ def test_us_zones
     assert !ActiveSupport::TimeZone.us_zones.include?(ActiveSupport::TimeZone["Kuala Lumpur"])
   end
 
+  def test_country_zones
+    assert ActiveSupport::TimeZone.country_zones("ru").include?(ActiveSupport::TimeZone["Moscow"])
+    assert !ActiveSupport::TimeZone.country_zones(:ru).include?(ActiveSupport::TimeZone["Kuala Lumpur"])
+  end
+
   def test_to_yaml
     assert_equal("--- !ruby/object:ActiveSupport::TimeZone\nname: Pacific/Honolulu\n", ActiveSupport::TimeZone["Hawaii"].to_yaml)
     assert_equal("--- !ruby/object:ActiveSupport::TimeZone\nname: Europe/London\n", ActiveSupport::TimeZone["Europe/London"].to_yaml)

railties/lib/rails/tasks/misc.rake

@@ -10,29 +10,46 @@ task about: :environment do
 end
 
 namespace :time do
+  desc 'List all time zones, list by two-letter country code (`rake time:zones[US]`), or list by UTC offset (`rake time:zones[-8]`)'
+  task :zones, :country_or_offset do |t, args|
+    zones, offset = ActiveSupport::TimeZone.all, nil
+
+    if country_or_offset = args[:country_or_offset]
+      begin
+        zones = ActiveSupport::TimeZone.country_zones(country_or_offset)
+      rescue TZInfo::InvalidCountryCode
+        offset = country_or_offset
+      end
+    end
+
+    build_time_zone_list zones, offset
+  end
+
   namespace :zones do
-    desc 'Displays all time zones, also available: time:zones:us, time:zones:local -- filter with OFFSET parameter, e.g., OFFSET=-6'
+    # desc 'Displays all time zones, also available: time:zones:us, time:zones:local -- filter with OFFSET parameter, e.g., OFFSET=-6'
     task :all do
-      build_time_zone_list(:all)
+      build_time_zone_list ActiveSupport::TimeZone.all
     end
 
     # desc 'Displays names of US time zones recognized by the Rails TimeZone class, grouped by offset. Results can be filtered with optional OFFSET parameter, e.g., OFFSET=-6'
     task :us do
-      build_time_zone_list(:us_zones)
+      build_time_zone_list ActiveSupport::TimeZone.us_zones
     end
 
     # desc 'Displays names of time zones recognized by the Rails TimeZone class with the same offset as the system local time'
     task :local do
       require 'active_support'
       require 'active_support/time'
+
       jan_offset = Time.now.beginning_of_year.utc_offset
       jul_offset = Time.now.beginning_of_year.change(month: 7).utc_offset
       offset = jan_offset < jul_offset ? jan_offset : jul_offset
-      build_time_zone_list(:all, offset)
+
+      build_time_zone_list(ActiveSupport::TimeZone.all, offset)
     end
 
     # to find UTC -06:00 zones, OFFSET can be set to either -6, -6:00 or 21600
-    def build_time_zone_list(method, offset = ENV['OFFSET'])
+    def build_time_zone_list(zones, offset = ENV['OFFSET'])
       require 'active_support'
       require 'active_support/time'
       if offset
@@ -47,7 +64,7 @@ namespace :time do
         end
       end
       previous_offset = nil
-      ActiveSupport::TimeZone.__send__(method).each do |zone|
+      zones.each do |zone|
         if offset.nil? || offset == zone.utc_offset
           puts "\n* UTC #{zone.formatted_offset} *" unless zone.utc_offset == previous_offset
           puts zone.name