Output line number in Rails log file

Use a decorator on Logger:

class LoggerDecorator
  def initialize(logger)
    @logger = logger
  end

  %w{debug info warn error fatal}.each do |method|
    eval(<<-eomethod)
      def #{method}(msg)
        @logger.#{method}(position) {msg}
      end
    eomethod
  end

  private
  def position
    caller.at(1).sub(%r{.*/},'').sub(%r{:in\s.*},'')
  end
end

logger.debug "Person attributes hash: #{@person.attributes.inspect} from line #{__LINE__}"

As of Rails 5, this is now baked in via:

ActiveRecord::Base.verbose_query_logs = true

See the documentation for more