Ruby generate unique integer for use as a primary key

Question

I need to generate a unique integer that will be assigned to the id field within a rails app. What is the best way of doing this. (using the usual auto increment is not an option and it has to be an integer.)

Answer 1

Ruby 1.9 has UUID version 4 generation included in module SecureRandom:

> require 'securerandom'
 => true
> SecureRandom.uuid
 => "4b3a56db-4906-4a44-a262-975d80c88195" 
> SecureRandom.uuid.gsub("-", "").hex
 => 56667719780883163491780810954791777167

A bit lengthy, but unique for sure.