Ruby on Rails: database changes logger

database_changes_logger.rb

# frozen_string_literal: true

### Usage

# Helps to understand how operation run affects the database state
# DatabaseChangesLogger.call(filename: 'output') { Operation.perform }

module DatabaseChangesLogger
  EVENTS_TYPE = 'sql.active_record'
  OPERATION_REGEX = /Update|Create/.freeze

  def self.call(filename: nil)
    return unless filename

    ActiveSupport::Notifications.subscribed(log_to(filename), EVENTS_TYPE) do
      yield
    end
  end

  def self.log_to(filename)
    lambda { |*args|
      event = ActiveSupport::Notifications::Event.new(*args)
      if event.payload[:name]&.match?(OPERATION_REGEX)
        filename = Rails.root.join(filename)
        File.open(Rails.root.join(filename), mode: 'a') do |f|
          f.write "\n"
          f.write(event.payload[:name])
          f.write "\n"
          f.write(event.payload[:sql])
          f.write "\n"
          f.write("=============================")
          f.write "\n"
        end
      end
    }
  end

end