Rails migration to add countries table and populate it with countries gem

add_countries_gem.sh

bundler add countries --version "~> 3.0.1" --require false

country.rb

class Country < ApplicationRecord
  enum region: { europe: 1, americas: 2, asia: 3, africa: 4, oceania: 5 }
end

rails_migration_create_countries.rb

require 'countries/iso3166'

class CreateCountries < ActiveRecord::Migration[7.0]
  def change
    create_table :countries do |t|
      t.string :name, limit: 64
      t.string :name_ru, limit: 64
      t.integer :region, limit: 1
      t.string :iso2, limit: 2
      t.string :phone_prefix, limit: 3
      t.string :currency_code, limit: 5
      t.boolean :eu_member, default: false
      t.string :official_languages, array: true, default: []

      t.timestamps
    end

    reversible do |dir|
      dir.up do
        %w[Europe Americas Asia Africa Oceania].each do |region|
          h_countries = []
          ISO3166::Country.find_all_countries_by_region(region).each do |c|
            h_countries << { name: c.name,
                             name_ru: c.translations['ru'],
                             region: region.downcase,
                             phone_prefix: c.country_code,
                             iso2: c.alpha2,
                             currency_code: c.currency_code,
                             official_languages: c.languages_official,
                             eu_member: c.data['eu_member'] }
          end
          Country.create(h_countries)
          puts "Create #{h_countries.size} #{Country.model_name.human(count: h_countries.size)} regione #{region}"
        end
      end
    end
  end
end