hstore_example.rb

require 'rom'
require 'rom-sql'

DB = Sequel.connect('postgres://localhost/rom_sql')
DB.execute('create extension if not exists hstore ')

DB.drop_table?(:strings)
DB.create_table(:strings) do
  primary_key(:id)
  hstore :value
end

rom = ROM.container(:sql, DB) do |config|
  config.relation(:strings) do
    schema(infer: true)

    def translated(language)
      project { [id, `coalesce(value->'#{ language }', value->'en')`.as(:value)] }
    end
  end
end

DB[:strings] << { id: 1, value: Sequel.hstore('en' => 'Hi', 'fr' => 'salut') }

puts rom.relation(:strings).translated('en') # {:id=>1, :value=>"Hi"}
puts rom.relation(:strings).translated('fr') # {:id=>1, :value=>"salut"}
puts rom.relation(:strings).translated('ru') # {:id=>1, :value=>"Hi"}