Code for Logging in Python Tutorial

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logger_simple.py

import logging # make a debug message logging.debug("This is a simple debug log") # make an info message logging.info("This is a simple info log") # make a warning message logging.warning("This is a simple warning log") # make an error message logging.error("This is a simple error log") # make a critical message logging.critical("This is a simple critical log") # just mapping logging level integers into strings for convenience logging_levels = { logging.DEBUG: "DEBUG", # 10 logging.INFO: "INFO", # 20 logging.WARNING: "WARNING", # 30 logging.ERROR: "ERROR", # 40 logging.CRITICAL: "CRITICAL", # 50 } # get the current logging level print("Current logging level:", logging_levels.get(logging.root.level)) # get the current logging format print("Current logging format:", logging.BASIC_FORMAT)

logger_basic.py

import logging # make a basic logging configuration # here we set the level of logging to DEBUG logging.basicConfig( level=logging.DEBUG ) # make a debug message logging.debug("This is a simple debug log") # make an info message logging.info("This is a simple info log") # make a warning message logging.warning("This is a simple warning log") # make an error message logging.error("This is a simple error log") # make a critical message logging.critical("This is a simple critical log")

logger_config.py

import logging logging.basicConfig( level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s", ) logging.info("This is an info message!")

logger_datefmt.py

import logging logging.basicConfig( level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s", datefmt="[%Y-%m-%d] %H:%M:%S", ) logging.info("This is an info message!")

logger_file.py

import logging import math logging.basicConfig(level=logging.DEBUG, handlers=[logging.FileHandler('logs.log', 'a', 'utf-8')], format="%(asctime)s %(levelname)-6s - %(funcName)-8s - %(filename)s - %(lineno)-3d - %(message)s", datefmt="[%Y-%m-%d] %H:%M:%S - ", ) logging.info("This is an info log") def square_root(x): logging.debug(f"Getting the square root of {x}") try: result = math.sqrt(x) except ValueError: logging.exception("Cannot get square root of a negative number") # or # logging.error("Cannot get square root of a negative number", exc_info=True) return None logging.info(f"The square root of {x} is {result:.5f}") return result square_root(5) square_root(-5)

logger_handlers.py

import logging # return a logger with the specified name & creating it if necessary logger = logging.getLogger(__name__) # create a logger handler, in this case: file handler file_handler = logging.FileHandler("file.log") # set the level of logging to INFO file_handler.setLevel(logging.INFO) # create a logger formatter logging_format = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s") # add the format to the logger handler file_handler.setFormatter(logging_format) # add the handler to the logger logger.addHandler(file_handler) # use the logger as previously logger.critical("This is a critical message!")