Generating a Short Uuid String Using Uuidtools in Rails

Generating a short UUID string using uuidtools In Rails

You don't need uuidtools for this. You can use Secure Random for this.

[1] pry(main)> require "securerandom"
=> true
[2] pry(main)> SecureRandom.hex(20)
=> "82db4d707c4c5db3ebfc349da09c991b7ca0faa1"
[3] pry(main)> SecureRandom.base64(20)
=> "CECjUqNvPBaq0o4OuPy8RvsEoCY="

Passing 4 and 5 to hex will generate 8 and 10 character hex strings respectively.

[5] pry(main)> SecureRandom.hex(4)
=> "a937ec91"
[6] pry(main)> SecureRandom.hex(5)
=> "98605bb20a"

Rails - Saved uuid's length is shorter than 32 characters

It was the SQLite database that was causing the issue - moved to MySQL database and it works as expected.

I need to generate uuid for my rails application. What are the options(gems) I have?

There are plenty of options, I recommend not to add additional dependencies and use SecureRandom which is builtin:

SecureRandom.uuid #=> "1ca71cd6-08c4-4855-9381-2f41aeffe59c"

See other possible formats here.

UUIDs in Rails3

Are you declaring another before_create method in your Image model? If so, you'll be overriding the one in the UUIDHelper module. You'll want to either declare the callback a different manner, or call super in the callback in your image model.

Edit: Maybe change the helper to look something like this:

module UUIDHelper
  def self.included(base)
    base.class_eval do
      before_create :set_uuid

      def set_uuid
        self.uuid = UUID.timestamp_create.to_s
      end
    end
  end
end

Convert a string representation of UUIDTools:UUID back to UUIDTools:UUID

Just use UUIDTools::UUID.parse:

 require "uuidtools"

 uuid = UUIDTools::UUID.random_create
 uuid.to_s
 #=> "cd833ba3-97c5-4615-a2a0-a6c3e56b24b2"

 UUIDTools::UUID.parse("cd833ba3-97c5-4615-a2a0-a6c3e56b24b2")
 #=> <UUID:0x3fd33d0ac184 UUID:cd833ba3-97c5-4615-a2a0-a6c3e56b24b2>

 UUIDTools::UUID.parse(uuid.to_s) == uuid
 #=> true

broken create, save, update, and destroy on Join record when using Postgres UUIDs in Rails

There are pros and cons to retaining both id and uuid. For JSON APIs that expose uuid, using Concerns would be a Rails-ish implementation.

app/models/user.rb

class User < ActiveRecord::Base

    include UserConcerns::Uuidable

end

app/models/concerns/user_concerns/uuidable.rb

module UserConcerns::Uuidable
    extend ActiveSupport::Concern

    included do
        before_save :ensure_uuid!
    end

    def ensure_uuid!
        self.uuid = generate_uuid if uuid.blank?
    end

    def generate_uuid
        # your uuid using uuid_generate_v4() here
    end

    def to_param
        uuid
    end
end

Above implementation leaves out the uuid generation but I think above answer has a link to that.

Generating GUIDs in Ruby

As of Ruby 1.9, uuid generation is built-in. Use the SecureRandom.uuid function.

For example:

require 'securerandom'
SecureRandom.uuid # => "96b0a57c-d9ae-453f-b56f-3b154eb10cda"

Same UUID being generated in multi-threaded application

You can synchronize uuid-generation method, and/or you can pregen uuid pool and generate more identificators in one thread when pool starts to deplete.

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