How to add custom parameter into Python logging formatter?

Question

I\'m using standard Python logging module with Flask framework. I want to write logs to file with the all records of users actions with custom parameter - %(username)s to loggin

Answer 1

Isn't the easier way to just subclass a Formatter and add your custom attribute to the LogRecord just before formatting?

For instance I use this code:

# A custom formatter to add the timestamp from the simulated clock.
class _Formatter(logging.Formatter):
  def format(self, record):
    record.simulated_clock = clock.get_time()
    return super(_Formatter, self).format(record)

# Creates a logger object.
def _create_logger():
  logger = logging.getLogger("simulation")
  logger.setLevel(kLevel)
  ch = logging.StreamHandler()
  ch.setLevel(kLevel)
  formatter = _Formatter("%(simulated_clock)s - %(levelname)s - %(message)s")
  ch.setFormatter(formatter)
  logger.addHandler(ch)

  return logger

I don't consider myself a Python expert, but it works for me....