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, I think 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.
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
My database column for the token is a unique index and I'm also using validates_uniqueness_of :token
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.
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.
Best Answer
-- Update --
As of January 9th, 2015. the solution is now implemented in Rails 5 ActiveRecord's secure token implementation.
-- Rails 4 & 3 --
Just for future reference, creating safe random token and ensuring it's uniqueness for the model (when using Ruby 1.9 and ActiveRecord):
Edit:
@kain suggested, and I agreed, to replace
begin...end..while
withloop do...break unless...end
in this answer because previous implementation might get removed in the future.Edit 2:
With Rails 4 and concerns, I would recommend moving this to concern.