rack-time-zone-middleware

Rack::TimeZoneMiddleware

Adding ability to detect timezone at UI side and get it within Rack/Rails via cookies with/o custom handler.

This gem created for usecase of loading detected TimeZone into Rails environment.
You can set cookie with TimeZone name at UI side(from Angular, React, Ember, Backbone or vanilla JS).
After that all XHR requests to your Rails/Rack backend can be identified by this Middleware.
In case when TimeZone name(s) is unsupported or key not found in cookies, middleware will fallback to defaults.

Installation

Add this line to your application's Gemfile:

gem 'rack-time-zone-middleware'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rack-time-zone-middleware

Logic in detail

1. UI
   1. Use something like JsTz to determine users time-zone.
   2. Write time-zone name to cookie.
   3. AngularJS Example
2. Ruby
   1. Use one of loading ways explained below (Usage).
   2. Provide cookie key_name with options, wich includes detected time-zone.
   3. Provide enironment key_name with options, where you store its value.
   4. Use env['key_name'] to access saved value from your application or controller.

Usage

Sinatra/Padrino application

require 'rack/time-zone-middleware'

# Default TimeZone handler.
use Rack::TimeZoneMiddleware

# Configured TimeZone handler.
use Rack::TimeZoneMiddleware, default_tz: 'Europe/Moscow', 
                              default_as_tz: 'Moscow', 
                              time_zone_key: 'dummy.time_zone'
                              cookie_key: 'dummy.time_zone'

# Your own TimeZone handler. All options & instance methods is available through middleware parameter.
use Rack::TimeZoneMiddleware do |middleware, env|
  request = ::Rack::Request.new(env)
    
  time_zone = request&.cookies['dummy.time_zone'] || middleware.options[:default_tz]
  env['dummy.time_zone'] = middleware.find_as_time_zone(time_zone)
  
  middleware.app.call(env)    
end

Rails application

# Default TimeZone handler.
config.middleware.use Rack::TimeZoneMiddleware

# Configured TimeZone handler.
config.middleware.use Rack::TimeZoneMiddleware, default_tz: 'Europe/Moscow', 
                                                default_as_tz: 'Moscow', 
                                                time_zone_key: 'dummy.time_zone'
                                                cookie_key: 'dummy.time_zone'

# Your own TimeZone handler. All options & instance methods is available through middleware parameter.
config.middleware.use Rack::TimeZoneMiddleware do |middleware, env|
  request = ::Rack::Request.new(env)
    
  time_zone = request&.cookies['dummy.time_zone'] || middleware.options[:default_tz]
  env['dummy.time_zone'] = middleware.find_as_time_zone(time_zone)
  
  middleware.app.call(env)    
end

In theory you can setup dynamic TimeZones detector(when its hash is managed from your Application, from Admin panel or something),
but in most of realizations what i saw, it is overhead.

Options

name	description
default_tz	optional, TimeZone name fallback value (default: 'Europe/Moscow')
default_as_tz	optional, ActiveSupport::TimeZone key name fallback value (default: 'Moscow')
cookie_key	optional, Cookie key name (default: 'dummy.time_zone')
time_zone_key	optional, Environment key name (default: 'dummy.time_zone')
time_zone_map	optional, TimeZone Hash or lambda, like {'Moscow' => 'Europe/Moscow'}. If not provided ActiveSupport TZInfo map will be tried.

AngularJS

TimeZone updater factory example via JsTz

web.services.factory('JsTz', ['ipCookie', function(ipCookie) {
  return {
    updateCookie: function() {
      tz = jstz.determine();
      name = tz.name(); 
      ipCookie('dummy.time_zone', name, { path: '/', expires: 21 });
      return name;
    }
  };  
}]);

Dependencies:

• Rack
• ActiveSupport(optional)

Contributing

1. Fork it ( https://github.com/merqlove/rack-time-zone-middleware/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Bug reports and pull requests are welcome on GitHub at https://github.com/merqlove/rack-time-zone-middleware.

Testing

$ rake test 

Development

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Copyright (c) 2016 Alexander Merkulov

MIT License