Working with ULIDs

A simple POC to demonstrate creating ULIDs as part of a Rails application (in the rails_example sub-directory) and reading them back in plain Ruby.

Setup

• Run bundle
• Create a local MySQL database called biz.
• Connect to MySQL and run the contents of the schema.sql file to create a widgets table.

Inserting data

Change to the rails_example directory:

• bundle
• bundle exec rails console

Create a few rows:

Widget.create(account_id: 99, name: 'test_from_rails', created_at: Time.now)

You'll notice the ULID ActiveRecord gem will create and assign a ULID ID to each model.

Reading data with Rails

You can read them back like so:

id = Widget.last.id

Widget.find(id) # => #<Widget id: "1DSD3VD20HESRZHP5TKER27BK", row_num: 62, account_id: 99, ...>

Reading data without Rails

You can also read the rows back using a special user-defined MySQL function as defined in ulid_fn.sql (original credit) by running:

bundle exec ruby read_all.rb

reading back all widgets, LIMIT 100
read 2 results
01DSD3RFGQ8VK4T5GN99J2HR9G|test_from_rails
01DSD3VD20HESRZHP5TKER27BK|test_from_rails

Or lookup an individual row like so:

bundle exec ruby read_one.rb 01DSD3VD20HESRZHP5TKER27BK

reading back 01DSD3VD20HESRZHP5TKER27BK
read 1 results
01DSD3VD20HESRZHP5TKER27BK|test_from_rails

Gotchas

ULIDs are 26 characters long and Base32 encoded. You'll notice that Rails will drop any leading '0' characters, but knows at save / read time to pad the string again.

So for example, an ID returned by Rails might be 1DSD3VD20HESRZHP5TKER27BK (25 characters). However, if you use this out of band, i.e. you copy it from a log file and try to lookup the value you won't find a record. The correct value should be01DSD3VD20HESRZHP5TKER27BK (26 characters; note the leading 0).