canvas-lms/lib/time_zone_helper.rb

71 lines
2.6 KiB
Ruby

# encoding: UTF-8
#
# Copyright (C) 2013 Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas 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 Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#
# time_zone_attribute :column, default: 'America/Denver'
# Makes column method return a TimeZone object, preferring Rails named zones
# even if serialized as tzinfo. column= method takes strings or TimeZone objects,
# and sets the attribute.
module TimeZoneHelper
module ClassMethods
def time_zone_attribute(attr, options = {})
self.time_zone_attribute_defaults ||= {}
time_zone_attribute_defaults[attr] = options[:default]
class_eval <<-CODE
def #{attr}
value = read_attribute(:#{attr})
value ||= self.class.time_zone_attribute_defaults[#{attr.inspect}] or return
TimeZoneHelper.rails_preferred_zone(ActiveSupport::TimeZone[value])
end
def #{attr}=(value)
if value.is_a?(String)
value = ActiveSupport::TimeZone[value]
end
write_attribute(:#{attr}, value.try(:name))
value
end
CODE
end
end
# make sure this is cached before we start querying other zones
ActiveSupport::TimeZone.all
# Returns a Rails named zone instead of tzinfo named zone, if one exists
def self.rails_preferred_zone(zone)
return nil unless zone
@reverse_map ||= Hash[ActiveSupport::TimeZone.all.map do |z|
# Rails allows several aliases that map to the same IANA zone; on the reverse
# mapping, exclude the aliases so that America/Lima doesn't come back as Quito
next if ["International Date Line West", "Guadalajara", "Quito",
"Edinburgh", "Bern", "St. Petersburg", "Volgograd", "Abu Dhabi",
"Islamabad", "Chennai", "Mumbai", "New Delhi", "Astana",
"Hanoi", "Osaka", "Sapporo", "Canberra", "Solomon Is.",
"Wellington"].include?(z.name)
[z.tzinfo.name, z]
end.compact]
@reverse_map[zone.name] || zone
end
def self.included(klass)
klass.send(:extend, ClassMethods)
klass.send(:class_attribute, :time_zone_attribute_defaults)
end
end