class ShortLink < ActiveRecord::Base
    after_initialize :default_values
    before_save(:on => :create) do generate_short_url end
    validates :long_url, :alternative_url, :presence => true

    private

    def generate_short_url
        self.short_url = (rand(8999999999)+1000000000).alphadecimal
        ShortLink.exists?(:short_url => self.short_url) ? generate_short_url : self.short_url
    end

   def default_values
     self.is_active ||= true
   end
end