UUID Rails tips

0_active_record_uuid_ids.rb

# config/initializers/active_record_uuid_ids.rb
Rails.application.config.generators do |generator|
  # Always use UUIDs for primary keys (when generating migrations)
  generator.orm :active_record, primary_key_type: :uuid
end

1_enable_uuid_migration.rb

class EnableUuidOssp < ActiveRecord::Migration[5.0]
  def change
    # Enable the UUID extension in PostgreSQL
    enable_extension "uuid-ossp"
  end
end

2_some_migration.rb

class CreateUsers < ActiveRecord::Migration[5.0]
  def change
    # "id: :uuid" should be generated automatically when
    # generating new migrations (with the above initializer)
    create_table :users, id: :uuid do |t|
      t.string :name
      t.string :email

      t.timestamps
    end
    add_index :users, :email
  end
end

3_some_migration.rb

class CreateIdentities < ActiveRecord::Migration[5.0]
  def change
    create_table :identities do |t|
      t.references :user, foreign_key: true, type: :uuid # Remember to specify the foreign key type!
      t.string :uid
      t.string :provider

      t.timestamps
    end
  end
end

4_misc_tips.md

Miscellaneous tips

• #find_each doesn't really work with UUIDs (the record IDs aren't guarenteed to be in any specific order)
• Remember to order collections in index views (there's no deterministic order by default)
• Nesting resources is extra bad with UUID IDs since they're so long. Avoid deep nesting!