FindLocatoinByIp Plugin

Easy way to find the "best guess" location/timezone info for a visitor to your Rails app.

Installation

./script/plugin install git://github.com/adamsalter/find_location_by_ip-plugin.git

This plugin depends on three gems (config/environment.rb):

config.gem 'tzinfo'
config.gem 'geoip'
config.gem 'geonames'

Technically the tzinfo gem is not needed by this plugin, but Rails will get confused by the timezone returned without it. (e.g. 'Australia/Sydney')

You will need to run the rake task to download/update the geoip db at least once:

rake geoip:update_db

by default the database file is placed in public/system, which is also a system dir created by capistrano deploys. (Don't forget to add public/system to your .gitignore file so that you don't add the geoip db to your repo)

Useage

Time.zone = FindLocationByIp.new(request.env['REMOTE_ADDR']).timezone

In application_controller.rb:

before_filter :select_location

private
  def select_location
    @location = FindLocationByIp.new(request.env['REMOTE_ADDR'])
    Time.zone = @location.timezone
  end

In views (haml shown):

= @location.city
= @location.country
-# etc.

Notes

1. Caching

The request to find the timezone is making at least one background request to "geonames.org" (and maybe more if other info is required) so it could be quite slow if you did this on every request.

I personally cache the request for every IP address, and, using my filestore_expires_in-plugin, set the expiry to 1 day. So for any IP address the request is only made at most once per day.

ip = request.env['REMOTE_ADDR']
cache_key = "controllers/application/select_timezone-%s" % [ip]

@location = Rails.cache.fetch(cache_key, :expires_in => 1.day) do
  FindLocationByIp.new(ip)
end
Time.zone = @location.timezone

2. TZInfo

The Timezone handling in Rails is a little confusing. Rails ActiveSupport::TimeZone basically comes with basic support, in the way of an offset and reduced list of timezones, but means Rails doesn't handle daylight savings by default. Full support is passed to the TZInfo gem.

... this also means things like the ActionView helper functions like time_zone_select don't support the Rails timezone naming if you use the TZInfo naming.

The following does work, but lists all possible TZInfo::Timezones:

#Example
@user.time_zone = FindLocationByIp.new(request.env['REMOTE_ADDR']).timezone

time_zone_select 'user', 'time_zone', nil, :model => TZInfo::Timezone

3. MaxMind GeoIP database

You can change the position of the maxmind db by creating an initializer in config/initializers

FindTimezone.system_dir = #{RAILS_ROOT} + '/my_custom_dir'

Thanks to Maxmind for a great geoip db. http://www.maxmind.com

Copyright (c) 2009 Adam @ Codebright.net, released under the MIT license