Rails model concern to support ordering of hstore_translated attributes with fallbacks

order_by_translated.rb

# frozen_string_literal: true
module OrderByTranslated

  extend ActiveSupport::Concern

  module ClassMethods

    def order_translated(*attributes)
      order(order_translated_sql(nil, *attributes))
    end

    def reorder_translated(*attributes)
      reorder(order_translated_sql(nil, *attributes))
    end

    private

    def order_translated_sql(table_prefix, *attributes)
      table_prefix ||= table_name
      attributes.map do |attribute|
        unless attribute.is_a?(Hash)
          attribute = { attribute => :asc }
        end

        attribute.map do |attr, direction|
          if %w(asc desc).include?(direction.to_s)
            full_attribute = table_prefix.present? ? "#{table_prefix}.#{attr}" : attr
            fields = I18n.fallbacks[I18n.locale].map { |locale| "#{full_attribute}_translations->'#{locale}'" }
            "coalesce(#{fields.join(', ')}) #{direction}"
          else
            order_translated_sql(attr.to_s, direction)
          end
        end
      end.flatten.join(', ')
    end
  end

end