logging_demo.py

"""
Examples of using Python's logging facility.

Run the file in Python and observe:
Which messages are actually printed on the console or to a file?
What information is in the message?

For details, see: https://docs.python.org/3/library/logging.html
"""
import logging


def logging_test(logger):
    """Log messages using each of the standard logging levels
       plus 1 custom log level.
    """
    # debug
    logging.debug("Context = {'data': 1234}")

    # info
    logging.info("some user has logged in.")

    # warning
    logging.warning("Someone attempted to login with id: markzaza")

    # level = logging.WARN + 5 (custom log level between WARN and ERROR)
    # create new log level named 'HUFE_WARNING'
    level = logging.WARN + 5  # custom log level

    def logForLevel(self, message, *args, **kwargs):
        if self.isEnabledFor(level):
            self._log(level, message, args, **kwargs)

    def logToRoot(message, *args, **kwargs):
        logging.log(level, message, *args, **kwargs)

    logging.addLevelName(level, "HUGE_WARNING")
    setattr(logging, "HUGE_WARNING", level)
    setattr(logging.getLoggerClass(), "huge_warning", logForLevel)
    setattr(logging, "huge_warning", logToRoot)

    # huge error
    logging.huge_warning("To warn that is going to be an error.")

    # error
    logging.error("Cannot get attribute a, skipped this function.")

    # critical or fatal
    logging.critical("No module named 'helloWorld' system shutting down.")
    print("You forgot to write logging_test")


def simple_config():
    """Configure logging using basicConfig for simple configuration.

    You should call this before creating any logging objects.
    You can call basicConfig only once.

    Some named attributes you can set using basicConfig are:

        filename = "name of a file to send log messages to"
        filemode = 'a' (append), 'w' (truncate & open for writing)
        format = a string describing format of log messages
        stream = name of a StreamHandler to use, cannot use with filename attribute
        level = the root logger level (threshold level for log msgs)

    See:  help(logging.basicConfig)
    https://docs.python.org/3/library/logging.html#logging.basicConfig
    """
    # use a custom format for log messages
    FORMAT = '%(asctime)s %(name)s %(levelname)s: %(message)s'
    logging.basicConfig(format=FORMAT)


def my_config():
    """Write your own logging configuration."""
    FORMAT = '[%(asctime)s] - %(levelname)s: %(message)s'
    logging.basicConfig(format=FORMAT, level=1, filename="tasks.log", filemode="w")


if __name__ == "__main__":
    # 1. Call basicConfig with the default settings
    # logging.basicConfig()

    # 2. Call simple_config to set the format of log messages.
    #    Comment out the above call (#1) to basicConfig for this.
    # simple_config()

    # 3. my_config() write your own logging configuration as
    #    described in the assignment.
    #    Comment out the above calls to simple_config and basicConfig.
    my_config()

    # Log some messages to the root logger using different logging levels.
    logger = logging.getLogger()
    logger.setLevel(logging.WARN)
    print("Logging to ", str(logger))
    logging_test(logger)

    mylogger = logging.getLogger()
    mylogger.setLevel(logging.DEBUG)  # log everything
    logging_test(mylogger)