Python uses the logging module to implement logging examples

Introduction to logging module

The logging module is a standard library module of Python. During the development process, this module can be used to flexibly complete log recording.
The logging module provides two logging methods:

1) Use the module-level functions provided by logging (logging.basicConfig, logging.debug, logging.info...)

2) Use the components of the logging module (loggers, handlers, filters, formatters)

Python logging log level

Table 1 Python logging log levels

level	Corresponding function	description
DEBUG	logging.debug()	The lowest level, used for small details, usually only when diagnosing problems, you will only care about these messages.
INFO	logging.info()	Used to record information about general events in the program, or to confirm that everything is working properly.
WARNING	logging.warning()	Used to indicate possible problems. It will not prevent the program from working, but it may in the future.
ERROR	logging.error()	Used to log errors, it causes the program to fail to do something.
CRITICAL	logging.critical()	The highest level, used to indicate a fatal error, which caused or will cause the program to stop working completely.

Instance

import logging
from logging.handlers import TimedRotatingFileHandler

class RecordLogs:
    def __init__(self, log_name, level=20, log_format="%(asctime)s,%(msecs)d %(name)s:%(levelname)s: [%(module)s(%(lineno)d)] %(message)s",
                date_format="%Y-%m-%d %H:%M:%S", console_print=True, log_file=None, when=None):
        self.log_name = log_name
        self.level = level
        self.log_format = log_format
        self.date_format = date_format
        self.console_print = console_print
        self.log_file = log_file
        self.when = when

    def print(self):
        # avoid duplicate printing
        if not self.console_print and not self.log_file:
            print("Error: Save log in file, but input not log file!")
            return
        log_dict = logging.Logger.manager.loggerDict
        print_flag = True if self.log_name not in log_dict else False
        when = None if self.when not in ["S", "M", "H", "D", "midnight"] else self.when
        if not print_flag:
            return
        # create logger
        logger = logging.getLogger(self.log_name)
        logger.setLevel(self.level)
        formatter = logging.Formatter(self.log_format, self.date_format)

        if self.console_print:
            # create handler，output log to console
            log_sh = logging.StreamHandler()
            log_sh.setFormatter(formatter)
            # logger add handler
            logger.addHandler(log_sh)
        if self.log_file:
            if when:
                logHandler = TimedRotatingFileHandler(self.log_file, when=when)
                logHandler.setFormatter(formatter)
                logger.addHandler(logHandler)
            else:
                fh = logging.FileHandler(self.log_file)
                fh.setFormatter(formatter)
                # logger add handler
                logger.addHandler(fh)
        return logger

if __name__ == "__main__":
    import time
    test_log = RecordLogs("log_test", console_print=True, log_file="C:/Users/user/Desktop/test.log", when=None, level=10).print()
    while True:
        test_log.info("info logger")
        test_log.error("error logger")
        test_log.warning("warning logger")
        test_log.debug("debug logger")
        time.sleep(10)

result:

to sum up:

The log printed during the running of the program through this module, especially the error information, is very important for troubleshooting, otherwise you have to manually execute the program every time to reproduce it again, which is very troublesome!