acts_as_csv.rb

require 'csv'
require 'activerecord-import'

module ActsAsCsv
  extend ActiveSupport::Concern

  class_methods do
    def filename
      if const_defined? :CSV_FILENAME
        self::CSV_FILENAME
      else
        name.underscore.pluralize
      end
    end

    def headers
      if const_defined? :CSV_HEADERS
        self::CSV_HEADERS
      else
        attribute_names - %w[id created_at updated_at]
      end
    end

    def export_csv
      CSV.open("#{filename}.csv", 'w', write_headers: true, headers: headers) do |csv|
        all.each { |row| csv << row.attributes.values_at(*headers) }
      end
    end

    def import_csv(csv_file)
      values = CSV.open("#{csv_file}.csv", headers: true).each_with_object([]) do |row, o|
        o << row.to_h
      end

      import values, validate: true, on_duplicate_key_ignore: true
    end
  end
end