为什么我没有得到 logger.info 的任何输出 [重复]

Question

import logging

# create logger
logger = logging.getLogger(__name__)

def start():
    print(f"logger.isEnabledFor(logging.INFO) 20: {logger.isEnabledFor(logging.INFO)}")
    print(f"logger.getEffectiveLevel(): {logger.getEffectiveLevel()}")
    logger.setLevel(logging.INFO)
    print(f"logger.setLevel(logging.INFO) done")
    print(f"logger.getEffectiveLevel(): {logger.getEffectiveLevel()}")
    print(f"logger.isEnabledFor(logging.INFO) 20: {logger.isEnabledFor(logging.INFO)}")
    logger.info('info message')
    logger.warning('warn message')
    logger.error('error message')
    logger.critical('critical message')

start()

为什么不记录：

info message

我知道 root logger 从 logging.WARNING 开始记录，但我想我已经修改了我的 logger 的有效级别，对吧？

无关：为什么 logger 模块被设计成使用起来如此笨拙？

Answer 1

添加此行logging.basicConfig(level=logging.INFO)

import logging
  
# create logger
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# rest of the code

结果：

logger.isEnabledFor(logging.INFO) 20: True
logger.getEffectiveLevel(): 20
logger.getEffectiveLevel(): 20
logger.isEnabledFor(logging.INFO) 20: True
INFO:__main__:info message
WARNING:__main__:warn message
ERROR:__main__:error message
CRITICAL:__main__:critical message 

为了让您的代码正常工作，您应该添加一个处理程序

ch = logging.StreamHandler()
ch.setLevel(logging.INFO)
logger.addHandler(ch)