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This branch (master) is home to a rewrite of the Carmen library. If you're currently using Carmen in your application, you probably want to see the 0.2.x branch, which will be maintained until version 1 is ready.

If you'd like become a maintainer of the project, please let me know.

Carmen- A repository of geographic regions for Ruby

A Little History

Carmen began its life as a replacement for Rails' country_select and state_select helpers. The API of the library was designed to facilitate a few view helpers and model validations, and that was about it.


It's been a few years since Carmen was released, and it has been used by a lot of projects. Many fine individuals have contributed code and data- I'm really happy with the way the community has improved the library. But this growth has brought to light many of the weaknesses in the current library and implementation.

I have decided that it is time to go back and rethink Carmen's data model and API, and in the process address some long standing issues. Carmen 1.0 will feature the following:

  • A new, cleaner API
  • Support for the old API via an optional require
  • More complete data via the iso-codes Debian package (idea borrowed from here)
  • A sane approach to internationalization, utilizing an existing i18n library.


  • Switch to a more complete data source (done)
  • Add the ability to overlay custom data on the dataset
  • Rewrite spike-level V2 API implementation
  • Provide a legacy api so existing users have an upgrade path ('carmen/legacy')
  • Separate Rails view methods out into a carmen-rails gem
  • i18n integration

How to Use Carmen

Carmen is designed to make it easy to access Country and region data. You can query for a country by name or code:

require 'carmen'
include Carmen

us = Country.named('United States')
=> <#Carmen::Country name="United States">

A Country object has some attributes that may be useful:

=> 'US'

=> 'USA'

us.code # alias for alpha_2_code
=> 'US'

=> "United States of America"

A Country (and its subregions) can contain subregions. In the US these are states, but other countries have other types of regions:

=> true

=> <#Carmen::Region name="Alabama" type="state">

Country#subregions returns a RegionCollection, which can be queried similarly to a Country to find, for instance, a specific state:

illinois = us.subregions.coded('IL')
=> <#Carmen::Region "Illinois">

Subregions support a smaller set of attributes than countries:
=> "Illinois"

=> "IL"

=> "state"

Some subregions may contain additional subregions. An example of this is Spain:

spain = Country.named('Spain')
andalucia = spain.subregions.first
=> <#Carmen::Region name="Andalucía" type="autonomous community">

=> true

=> <#Carmen::Region name="Almería" type="province">