Generating unique random string for identifying a record

Question

I have a requirement to be able to identify a record in a table, in this case a user table, by a unique key which does not give away the ordering of the records in the table.

Currently I have primary key field and the routes that are generated look like:

/users/1

However, I'd like to be able to generate a route like:

/users/kfjslncdk

I can wire everything up on the route side, database side etc.. but I'm not sure what the best way to generate a unique string identifier would be in rails. I'd like do something like:

before_save :create_unique_identifier

def create_unique_identifier
    self.unique_identifier = ... magic goes here ...
end

I was thinking I could use the first part of a guid created using UUIDTools, but I'd need to check to make sure it was unique before saving the user.

Any advice would be greatly appreciated!

Answer 1

before_create :create_unique_identifier

def create_unique_identifier
  loop do
    self. unique_identifier = SecureRandom.hex(5) # or whatever you chose like UUID tools
    break unless self.class.exists?(:unique_identifier => unique_identifier)
  end
end

Answer 2

Ruby 1.9 includes a built-in UUID generator: SecureRandom.uuid