Active Record – Collations

Allows basic management of ICU collations in Postgres.

class UpdateNaturalDeCollation < ActiveRecord::Migration[8.1]
  def change
    drop_collation(:natural_de)
	create_collation(
      :natural_de,
      'de-u-kn-true-ks-level1-ka-shifted-kv-symbol'
  	)
  end
end

See Postgres collation documentation on how to write ICU locale strings.

Setup

Add activerecord-collations to your dependencies. Include the collation concern into your models to get access to the collate class method.

class ApplicationRecord < ActiveRecord::Base
  primary_abstract_class

  include ActiveRecord::Collation
end

The collate method creates an ARel expression for the column with a certain collation.

scope :ordered, -> { order(collate(:title, "natural_#{I18n.locale}") }
scope :ordered_de, -> { order(collate(:title, :natural_de)) }

Alternatively you can build it yourself:

Arel::Nodes::InfixOperation.new(
  'COLLATE',
  arel_table[:title],
  Arel.sql('natural_de')
)

Development

Run tests in this repository with rake. Migrations are exercised by running them in the dummy application.

cd test/dummy
rm -f db/schema.rb && RAILS_ENV=test rake db:drop db:create db:migrate