HasUniqueThreeLetterCode

User requirements: Assign a case-insensitive unique three-letter code to each record in a scope, based loosely on some other attribute of the record.

Example: Within the office, we refer to each client by a TLA (three-letter acronym). We want to store the TLA's in our database automatically when we create a client, and we want the TLA to be loosely based on the client's name. The National Rifle Association is the NRA. The Office of Management and Budget is the OMB. The National Restaurant Association--well, NRA is already taken, so how about NRX?

Solution: HasUniqueThreeLetterCode

Add this line to your application's Gemfile:

gem 'has_unique_three_letter_code'

And then execute:

$ bundle

Or install it yourself as:

$ gem install has_unique_three_letter_code

class Client < ActiveRecord::Base
  attr_accessible :tla, :name, :tla_group

  include HasUniqueThreeLetterCode
  def needs_tla?
    # Maybe clients that went out of business can have their TLA retired.
    # Or maybe you don't need a TLA for a client with a monosyllabic name
  end
  has_unique_three_letter_code :tla,
    :source => :name, # The field we use to generate the TLA.  This can be another column in this table, or any other method an instance of the class responds_to?, so if it's in another table, just `delegate :name, :to => :the_associated_record`
    :uniqueness => { :scope => :tla_group }, # uniqueness constraints are passed directly to validates_uniqueness_of
    :leave_blank => { :unless => :needs_tla? } # :leave_blank supports keys :if and :unless.  Values can be Procs or symbolized instance method names.
end

$ COVERAGE=true rspec

(The environment variable 'COVERAGE' is optional and runs it with simplecov)

1. Support options for lowercase and case-sensitive.
2. Support N-letter codes.
3. Before resorting to a random letter, search for an available combination using the first two letters of a word.
4. When choosing a random letter, run through them randomly without repetition, instead of alphabetically.
5. Add support for Rails 4

1. Fork it
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 new Pull Request