A small gem for calculating zodiac sign from a date of birth
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zodiac is a simple gem for getting a zodiac sign from a given date of birth. It extends Time, Date and DateTime objects with a #zodiac_sign method and can also extend ActiveRecord::Base with several instance (delegated to some date attribute of the model object) and class methods (allowing you to search for objects with a certain zodiac sign)


gem install zodiac

Or, if you want to extend your rails app, add the following to the Gemfile:

gem 'zodiac'

and run bundle install.


Time/Date/DateTime usage

require 'zodiac'
Time.now.zodiac_sign                  # => "Aries"
require 'date'
Date.new(2011, 1, 1).zodiac_sign      # => "Capricorn"
DateTime.new(2011, 4, 30).zodiac_sign # => "Taurus"

#zodiac_sign returns values using I18n with "zodiac.#{sign}" path, so if you want your own translations, you can put them in your locale with keys like zodiac.aries, zodiac.taurus etc. See examples here.

There are also predicate methods which return true if the date is matching the specified zodiac sign (and false otherwise).

Date.new(1989, 2, 26).pisces? # => true
Time.gm(1978, 7, 12).gemini?  # => false

ActiveRecord usage

The first thing you need to do is to add gem 'zodiac' to your Gemfile as described before.

To add zodiac methods to your model you just call a zodiac_reader macro in your model passing it the name of the attribute containing the date of birth:

class Person < ActiveRecord::Base
  zodiac_reader :dob

and then you'll be able to get zodiac sign of your object just by calling #zodiac_sign on it:

@person = Person.first
@person.zodiac_sign    # => "Taurus"

You can also use the predicate methods like #libra?

@person.libra?         # => false
@person.taurus?        # => true

If you also need to search for all geminis in your people table, you should add an integer field containing a numerical id of the person's zodiac sign to that table. zodiac can help you with that - it already includes a generator zodiac:migration which creates a migration adding that field to your table (and an index on that field). You should specify the name of your model class as the first argument while calling the generator:

rails generate zodiac:migration Person

(Note that you must call zodiac_reader in your model in order for the migration to run correctly - after creating a new field the migration tries to update it for all existing records)

Now zodiac_reader macro in your model gives you some scopes to filter objects by a zodiac sign:

Person.with_zodiac_sign('libra') # returns all libras
Person.gemini                    # all the geminis

To keep the consistency of a zodiac sign with the date of birth, zodiac_reader also installs a before_save filter to your model, which updates the sign field every time you change the date-of-birth attribute.

If you don't like the name of the field containing zodiac sign (by default it's zodiac_sign_id), you can customize it, passing the wanted name as an option to zodiac_reader in your model and then as the second parameter to the generator:

class Person < ActiveRecord::Base
  zodiac_reader :dob, :sign_id_attribute => :custom_sign_id
rails generate zodiac:migration Person custom_sign_id

Included locales


  • 0.1 Initial version with Time/Date/DateTime extension and [:ru, :en] locales
  • 0.1.1 Added Brazilian Portuguese locale (thanks jeffrydegrande)
  • 0.2 Added ActiveRecord support (scopes, predicate methods and delegating #zodiac_sign to date-of-birth attribute)
  • 0.2.1 Added Japanese locale (thanks hamakn)
  • 0.2.2 Added Italian locale (thanks lucapette)


  1. Rdoc coverage of everything

  2. Other ORMs support (DataMapper, Sequel, Mongoid)

  3. ActiveRecord 4.0 support (extending AR::Model instead of AR::Base)


Fork the repository, push your changes to a topic branch and send me a pull request.