title: Best way to create unique token in Rails?
body: <p>Here's what I'm using. The token doesn't necessarily have to be heard to guess, it's more like a short url identifier than anything else, and I want to keep it short. I've followed some examples I've found online and in the event of a collision, <em>I think</em> the code below will recreate the token, but I'm not real sure. I'm curious to see better suggestions, though, as this feels a little rough around the edges.</p>
  
  <pre><code>def self.create_token
      random_number = SecureRandom.hex(3)
      "1X#{random_number}"
  
      while Tracker.find_by_token("1X#{random_number}") != nil
        random_number = SecureRandom.hex(3)
        "1X#{random_number}"
      end
      "1X#{random_number}"
    end
  </code></pre>
  
  <p>My database column for the token is a unique index and I'm also using <code>validates_uniqueness_of :token</code> on the model, but because these are created in batches automatically based on a user's actions in the app (they place an order and buy the tokens, essentially), it's not feasible to have the app throw an error.</p>
  
  <p>I could also, I guess, to reduce the chance of collisions, append another string at the end, something generated based on the time or something like that, but I don't want the token to get too long.</p>