Rails 4.1 added support for Enums to be used in models. You can check out the release notes here.

Generally, these are supposed to be used for tracking internal states and should not be exposed to the user. If you're a rebel however, you can easily use these for user-definable states.

Let's say you have a User model. We define the enum as follows:

class CreateUsers < ActiveRecord::Migration
	def change
    	create_table :users do |t|
        	t.string :username
            t.string :email
            t.string :encrypted_password
            # ...
            t.integer :role
    end
end

First, we create a constant for our list of semesters, then create a friendly, human-readable version for displaying to the user.

class User > ActiveRecord::Base
    enum role: %i[admin moderator user banned]
    ROLE_SELECT = roles.map {|r| [r.to_s.titleize, roles.index(r)] }
end

Using SimpleForm, we can use either a select box or radio buttons to pick our options.

= simple_form_for @user do |f|
  = f.input :role, as: :select, collection: User.const_get(:ROLE_SELECT), selected: User.roles[@user.role]

Easy peasy!

API: http://api.rubyonrails.org/classes/ActiveRecord/Enum.html