Python logger格式化未格式化字符串 [英] Python logger formatting is not formatting the string

问题描述

以下是mylogger.py的内容:

def get_logger(name='my_super_logger'):
    log = logging.getLogger(name)
    log.setLevel(logging.DEBUG)
    formatter = logging.Formatter(fmt='%(asctime)s %(name)s %(message)s',
                                  datefmt='%m/%d/%Y %I:%M:%S %p')
    if not len(log.handlers):
        ch = logging.StreamHandler()
        ch.setLevel(logging.DEBUG)
        ch.setFormatter(formatter)
        log.addHandler(ch)
    # print(id(log))
    return log

以及以下是myscript.py的内容:

from mylogger import get_logger

_logger = get_logger()

_logger.info('trying info')
_logger.debug('trying debug')

但是我面临两个问题.它两次打印日志，并且每次格式化程序都不起作用:

However I am facing two issues. It prints the logs twice and formatter is not working everytime:

09/18/2015 09:59:54 PM my_super_logger trying info 
INFO:my_super_logger:trying info 
09/18/2015 09:59:54 PM my_super_logger trying debug 
DEBUG:my_super_logger:trying debug 

我的get_logger代码到底有什么问题?

What exactly is the issue with my get_logger code?

我需要自定义格式.但是我发现，如果不添加处理程序，则无法添加formatter.这就是为什么我添加了StreamHandler的原因.在答案中提到了if阻止的原因.否则，我将打印出重复的日志消息.

I need a custom formatting. However I found out that without adding a handler I cannot add a formatter. So that's why I have added StreamHandler. And the reason for if block is mentioned in this answer. Without that, I would get duplicate log messages printed.

推荐答案

root记录程序也正在发出该消息.通过以下方式停止传播到根部:

The root logger is also emitting the message. Stop propagation up to the root with:

log.propagate = False

如果您要格式化 all 日志输出(因此消息将传播到记录器)，请为根记录器设置格式化程序.

If you wanted to format all log output (so messages propagated up to the logger), set the formatter for the root logger.

您可以通过 logging.basicConfig() 调用来执行此操作如果尚未将任何内容发送到记录器，或者通过遍历根记录器的logger.handlers列表；如果愿意，您可以选择任何StreamHandlers:

You can do so with a logging.basicConfig() call provided nothing has yet been sent to the loggers, or by looping over the logger.handlers list of the root logger; you could pick out any StreamHandlers if you so wish:

root_logger = logging.getLogger()  # no name
for handler in root_logger.handlers:
    if isinstance(handler, logging.Streamhandler):
        handler.setFormatter(formatter)

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