Python logging module: The ultimate question-answering guide

Basic usage

How do I add a loglogger to my script?

import logging

# 创建一个日志记录器
logger = logging.getLogger(__name__)

How to log messages?

logger.info("这是信息消息")
logger.warning("这是警告消息")
logger.error("这是错误消息")

Configuring logging

How to change logging level?

# 设置根日志记录器的级别为 INFO
logging.basicConfig(level=logging.INFO)

# 设置特定日志记录器的级别为 DEBUG
logging.getLogger("mymodule").setLevel(logging.DEBUG)

How to output log records to a file?

# 将日志记录输出到名为 "mylog.txt" 的文件
logging.basicConfig(filename="mylog.txt")

Advanced Configuration

How to customize the logging format?

# 自定义日志记录格式
logging.basicConfig(fORMat="%(asctime)s %(levelname)s:%(message)s")

How to use multiple handlers?

# 创建一个文件处理程序和一个控制台处理程序
file_handler = logging.FileHandler("mylog.txt")
console_handler = logging.StreamHandler()

# 将处理程序添加到日志记录器
logger.addHandler(file_handler)
logger.addHandler(console_handler)

Custom handler

How to create a custom handler?

import logging

# 创建一个自定义处理程序
class MyHandler(logging.Handler):
def emit(self, record):
# 自定义处理记录的方式

# 添加自定义处理程序到日志记录器
logger.addHandler(MyHandler())

How to filter logging messages?

import logging

# 创建一个过滤
filter = logging.Filter("mymodule")

# 将过滤添加到处理程序
handler.addFilter(filter)

Debugging and Troubleshooting

Logging output not found?

• Check that the logging level is set correctly.
• Check if the handler has been added to the logger.
• Make sure the log file has write permission.

Too much logging information?

• Reduce logging level.
• Use filtering to exclude unwanted messages.

in conclusion

python The logging module provides powerful functionality to help you track, log, and debug the health of your application. By understanding the basic concepts and advanced techniques described in this article, you can effectively configure logging and create custom solutions tailored to your specific needs.

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