Using UUID for SQLite in Rails

Most tutorials online are on how to do this for Postgres. Here’s how to do it with SQLite and Rails 6+

Assume we’re creating a User model.

class CreateUsers < ActiveRecord::Migration[6.1]
  create_table :users, id: false do |t|
    t.string :id, null: false
  end
  add_index :users, :id, unique: true
end

You can use a string or blob type. As a general rule of thumb (YMMV) blob is slightly more performant and uses less disk space but is less easy to work with.

Now we need to make sure a UUID is assigned when you save the model.

class User < ApplicationRecord
  before_create :maybe_assign_id
  
  # ...
  
  def maybe_assign_id
    self.id = SecureRandom.uuid if self.id.blank?
  end
end

Take it for a spin:

2.7.4 :003 > User.create
   (0.7ms)  SELECT sqlite_version(*)
  TRANSACTION (0.1ms)  begin transaction
  User Create (0.5ms)  INSERT INTO "users" ("id", "created_at", "updated_at") VALUES (?, ?, ?)  [["id", "d48ccbbc-ff16-4815-acf5-30522bf4c30f"], ["created_at", "2022-09-16 17:13:26.189529"], ["updated_at", "2022-09-16 17:13:26.189529"]]
  TRANSACTION (1.1ms)  commit transaction
 => #<User id: "d48ccbbc-ff16-4815-acf5-30522bf4c30f", currency_amount: 0, currency_code: "USD", created_at: "2022-09-16 17:13:26.189529000 +0000", updated_at: "2022-09-16 17:13:26.189529000 +0000">

Other resources

• You can use UUID v6 for time-based UUIDs. See gem uuid_v6.
• If you want a solution in a gem you can use activeuuid.