AutoCommit Mon Jun 8 22:03:14 CEST 2015

app/models/key.rb

@@ -0,0 +1,11 @@
+class Key < ActiveRecord::Base
+  attr_accessible :expire, :is_valid,  :type, :user_id
+  belongs_to :parent, :polymorphic => true
+  belongs_to :user
+  before_create :create_unique_identifier
+  def create_unique_identifier
+    begin
+      self.uuid = SecureRandom.hex(10) # or whatever you chose like UUID tools
+    end while self.class.exists?(:uuid => uuid)
+  end
+end