Generating Hex-ULIDs in Ruby

In the previous post, we explored how to generate a base16-encoded ULIDs with only native SQLite functions. In the end, we built an expression that will generate hex-ULIDs for us:

SELECT PRINTF('%012X', CAST(ROUND((JULIANDAY('now') - 2440587.5)*86400000) AS INTEGER)) | HEX(RANDOMBLOB(10)) AS qulid;

This expression will return a 32 character string like 0184E14B9D33DF0EA40E00D20FC31406, which encodes a 48 bit timestamp and an 80 bit random portion, producing a 128 bit blob just like ULIDs and UUIDs. The string is composed of an 12 character base16-encoded timestamp and a 20 character random portion.

But what if we need to generate a hex-ULID in Ruby?

Ruby Hex-ULIDs

Let’s convert our SQLite expression into a Ruby function.

class HexULID
  def self.generate(moment: nil, entropy: nil)
    moment = (Time.now.to_r * 1000).to_i
    entropy = SecureRandom.random_bytes(10)
 
    hex_timestamp = sprintf('%012X', moment)
    hex_randomness = entropy.bytes.map { |byte| sprintf('%02X', byte) }.join
    hex_timestamp << hex_randomness
  end
end

This HexULID class will generate strings in exactly the same format as our SQLite expression. This will allow us to generate our hex-ULIDs in either Ruby or SQLite, which will make schema migrations and various code patterns easier.

In the future, we will explore how to make a schema migration to make use of such hex-ULIDs in a new or existing Rails project.