Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


Gem Version Build Status Coverage Status Code Climate License

Youyouaidi is a Ruby Gem that offers a UUID class for generating, parsing, validating and converting UUIDs into / from shorter representations.

While a UUID consists of 36 characters – 32 hexadecimal characters, divided by four dashes into five subgroups – the short representation (invoked via #to_short_string) consists of exactly 22 digit and lower- and uppercase characters.

This is what a valid, random (version 4) UUID looks like:

                          version    either 8, 9
                           number    a, or b
                                ▼    ▼
# chars in group:     8   | 4  | 4  | 4  |    12

As shown, the first digit of the third group indicates the UUID version. The first digit of the fourth group always has to be one of either 8, 9, a, or b. All other digits are randomly assigned hexadecimals.

And this is the same UUID in its short format: 6aUS5foeLu2VGDspRPc7bz.

For UUID generation, the SecureRandom.uuid method is used which generates valid, random version 4 UUIDs.

Find out more about UUIDs and the different versions on Wikipedia.


Add this line to your application's Gemfile:

gem 'youyouaidi'

And then execute:

$ bundle

Or install it yourself as:

$ gem install youyouaidi


For usability, UUID(...) is patched into the kernel as a shorthand call to Youyouaidi::UUID.parse(...). Also, UUID is patched as a reference for the class Youyouid::UUID.

Initializing UUIDs

uuid_string = '550e8400-e29b-41d4-a716-446655440000' # A valid UUID in string format, has exactly 32 hexadecimal characters in 5 groups
uuid_short  = '2AuYQJcZeiIeCymkJ7tzTW'               # Same UUID in its short format, has exactly 22 characters of [0-9a-zA-Z]

uuid = UUID uuid_string   # creates new Youyouaidi::UUID object, patches Youyouaidi::UUID.parse uuid_string into kernel.
# => #<Youyouaidi::UUID:0x000001021f2590 @converter=Youyouaidi::Converter, @uuid="550e8400-e29b-41d4-a716-446655440000">

# Alternatively a short UUID can be passed:
uuid = UUID uuid_short    # creates similar Youyouaidi::UUID object
# => #<Youyouaidi::UUID:0x00000102201b80 @converter=Youyouaidi::Converter, @uuid="550e8400-e29b-41d4-a716-446655440000">

# To generate a new random UUID simply do not pass a parameter:
new_uuid = UUID()         # generates a random UUID version 4 using the SecureRandom.uuid method
# => #<Youyouaidi::UUID:0x00000102201b80 @converter=Youyouaidi::Converter, @uuid="27f8bc29-be8e-4dc7-ab30-0295b2a5e902">

Validity check and conversions

The validity check UUID.valid? uuid_string checks, if UUID contains exactly 32 hexadecimal characters which are divided by four dashes ('-') into five groups of sizes 8, 4, 4, 4, and 12. Also, it validates that the first character of the fourth group is either a 8, 9, an a, or a b.

uuid_string = '550e8400-e29b-41d4-a716-446655440000' # A valid UUID in string format
uuid = UUID uuid_string

UUID.valid? uuid_string # Checks if `uuid_string' is a valid UUID, same as Youyouaidi::UUID.valid? uuid_string
# => true

uuid.to_s               # Returns the string representation of the UUID object
# => '550e8400-e29b-41d4-a716-446655440000'

uuid.to_short_string    # Returns the short string representation of the UUID object, #to_param is an alias for this method
# => '2AuYQJcZeiIeCymkJ7tzTW'

Comparing UUIDs

uuid_string  = '550e8400-e29b-41d4-a716-446655440000' # A valid UUID in string format
uuid         = UUID uuid_string
similar_uuid = UUID uuid_string
other_uuid   = UUID '00000000-1111-2222-aaaa-eeeeeeeeeeee'

uuid == similar_uuid # Two UUID objects representing same UUID (#=== behaves similar for this)
# => true

uuid == other_uuid   # Two UUID objects representing different UUIDs (#=== behaves similar for this)
# => false

uuid == uuid_string  # Comparing a UUID object and its string representation with `=='
# => false

uuid === uuid_string # Comparing a UUID object and its string representation with `===' (case insensetive)
# => true


  1. Fork it ( )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


Ruby Gem youyouaidi offers a UUID class for parsing, validating and encoding UUIDs







No packages published