Rails 3: Generate unique codes (coupons)

Question

What's the best way to generate unique codes to use as coupon codes?

Thanks.

Answer 1

What you want is to generate a GUID. See here:

guid generator in ruby

Answer 2

You can do something like this too:

chars = ('a'..'z').to_a + ('A'..'Z').to_a
def String.random_alphanumeric(size=16)
    (0...size).collect { chars[Kernel.rand(chars.length)] }.join
end

But then you would have to compare against a database to make sure it is not used yet.

From here.

Answer 3

In Ruby's standard library there is SecureRandom for this:

SecureRandom.hex(3)

The length of the output is double of what the length input specified.

Answer 4

Note: There is a same question

Recently I wrote coupon-code gem that does exactly the same thing. The algorithm borrowed from Algorithm::CouponCode CPAN module.

A coupon code should not only be unique, but also easy to read and type while it still is secure. Neil's explanation and solution is great. This gem provides a convenient way to do it and a bonus validation feature.

>> require 'coupon_code'
>> code = CouponCode.generate
=> "1K7Q-CTFM-LMTC"
>> CouponCode.validate(code)
=> "1K7Q-CTFM-LMTC"
>> CouponCode.validate('1K7Q-CTFM-LMTO') # Invalid code
=> nil

Answer 5

Maybe try this, seems to be more proof than just generating some random key. They say: UUID generator for producing universally unique identifiers based on RFC 4122 (http://www.ietf.org/rfc/rfc4122.txt). http://rubygems.org/gems/uuid

gem install uuid
cd /myproject/path
uuid-setup

In your code

require_gem 'uuid'
my_unique_id_var = UUID.new

Reference: http://railsforum.com/viewtopic.php?id=12616#p44545

Answer 6

If you don't want to waste comparing against the database (not a super expensive operation), you can guarantee that Time is always unique because it only occurs once

md5(Time.now.to_i.to_s+Time.now.usec.to_s)