什么是Python的默认日志记录格式化程序？

Question

我正在尝试破译日志中包含的信息(日志记录设置使用默认格式化程序).该文件规定:

对记录进行格式化 - 如果设置了格式化程序,请使用它.否则,请使用模块的默认格式化程序.

但是,我找不到任何实际说明这种默认格式的引用.

Answer 1

默认格式位于此处:

BASIC_FORMAT = "%(levelname)s:%(name)s:%(message)s"  

该格式的代码会告诉你如何定义它.这是一个关于如何自定义它的示例.

import sys
import logging

logging.basicConfig(
    level=logging.DEBUG,
    format="[%(asctime)s] %(levelname)s [%(name)s.%(funcName)s:%(lineno)d] %(message)s",
    datefmt="%H:%M:%S",
    stream=sys.stdout)

logging.info("HEY")

结果如下:

[26/May/2013 06:41:40] INFO [root.<module>:1] HEY

Answer 2

@rh0dium's and @Blender's answers contradict each other but they're both correct... just incomplete.

As of Python 3.10:

• If you create a handler without specifying a formatter, the default format is "%(message)s".
• If you call logging.basicConfig it sets up a handler on the root logger with a formatter that defaults to "%(levelname)s:%(name)s:%(message)s".
  • Note that logging.info, logging.warning etc will automatically call logging.basicConfig() if you haven't called it already.
  • But calling the root logger directly (like logging.getLogger().info(...)) won't call logging.basicConfig().

So the actual behaviour depends on whether you've ever called logging.basicConfig or logging.info/logging.warning/etc.

$ python3
Python 3.10.4 (main, Apr  2 2022, 09:04:19) [GCC 11.2.0] on linux
>>> import logging
>>> root = logging.getLogger()
>>> root.warning("W")
W
>>> logging.warning("W")
WARNING:root:W
>>> root.warning("W")
WARNING:root:W
>>> mylogger = logging.getLogger("mylogger")
>>> mylogger.addHandler(logging.StreamHandler())
>>> mylogger.propagate = False
>>> mylogger.warning("W")
W

Answer 3

import logging
print(logging.BASIC_FORMAT)

旧线程，但这首先出现在我的Google搜索结果中以查询“ python logging default format”，因此我认为我应该添加答案。

也有一些评论询问人们如何独自发现这一点。这是很自然的事情：

import logging
print(dir(logging))

BASIC_FORMAT在其中，实际上，对于我而言，它是结果中的第一项。