migrate existing time zones to tzinfo format

db/migrate/20211005080304_tzinfo_time_zones.rb

@@ -0,0 +1,75 @@
+#-- encoding: UTF-8
+
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2021 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+class TzinfoTimeZones < ActiveRecord::Migration[6.1]
+  def up
+    zone_mappings = ActiveSupport::TimeZone
+                    .all
+                    .map do |tz|
+                      [
+                        [tz.name, tz.tzinfo.canonical_zone.name],
+                        # Some entries seem to already be in that format so we leave them unchanged
+                        [tz.tzinfo.canonical_zone.name, tz.tzinfo.canonical_zone.name]
+                      ]
+                    end
+                    .flatten(1)
+
+    migrate_time_zone(zone_mappings)
+  end
+
+  def down
+    zone_mappings = ActiveSupport::TimeZone
+                      .all
+                      .map do |tz|
+                        [tz.tzinfo.canonical_zone.name, tz.name]
+                      end
+
+    migrate_time_zone(zone_mappings)
+  end
+
+  protected
+
+  def migrate_time_zone(mappings)
+    execute <<~SQL.squish
+      WITH source AS (
+        SELECT id, settings || jsonb_build_object('time_zone', to_zone) settings
+      FROM user_preferences
+      LEFT JOIN (SELECT * FROM (#{Arel::Nodes::ValuesList.new(mappings).to_sql}) as t(from_zone, to_zone)) zones
+        ON zones.from_zone = user_preferences.settings->>'time_zone'
+      )
+
+      UPDATE user_preferences sink
+      SET settings = source.settings
+      FROM source
+      WHERE source.id = sink.id
+      AND sink.settings->'time_zone' IS NOT NULL
+    SQL
+  end
+end