将日志级别设置为logging.DEBUG或logging.INFO无效

Question

我正在尝试做一个非常简单的日志记录设置。我只想将所有日志输出发送到终端和日志文件。我在Real Python上找到了以下示例，演示了流和文件日志处理程序的设置：

# logging_example.py

import logging

# Create a custom logger
logger = logging.getLogger(__name__)

# Create handlers
c_handler = logging.StreamHandler()
f_handler = logging.FileHandler('file.log')
c_handler.setLevel(logging.WARNING)
f_handler.setLevel(logging.ERROR)

# Create formatters and add it to handlers
c_format = logging.Formatter('%(name)s - %(levelname)s - %(message)s')
f_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
c_handler.setFormatter(c_format)
f_handler.setFormatter(f_format)

# Add handlers to the logger
logger.addHandler(c_handler)
logger.addHandler(f_handler)

logger.warning('This is a warning')
logger.error('This is an error')

## Log Output
# 2019-08-31 22:16:02,478 - __main__ - WARNING - This is a warning
# 2019-08-31 22:16:02,478 - __main__ - ERROR - This is an error

这将如您所期望的那样记录到控制台和文件中。但是，当我修改程序以便它也记录 INFO 时，如下所示：

import logging

# Create a custom logger
logger = logging.getLogger(__name__)

# Create handlers
c_handler = logging.StreamHandler()
f_handler = logging.FileHandler('file.log')
c_handler.setLevel(logging.DEBUG)
f_handler.setLevel(logging.DEBUG)

# Create formatters and add it to handlers
c_format = logging.Formatter('%(name)s - %(levelname)s - %(message)s')
f_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
c_handler.setFormatter(c_format)
f_handler.setFormatter(f_format)

# Add handlers to the logger
logger.addHandler(c_handler)
logger.addHandler(f_handler)


logger.warning('logs')
logger.error('logs')
logger.info('should log but doesn\'t')
logger.debug('should log but doesn\'t')

## Log Output
# __main__ - WARNING - logs
# __main__ - ERROR - logs

我究竟做错了什么？任何帮助将不胜感激！

Answer 1

您还需要调用setLevel(level)对象logger本身，因为默认情况下，它将使用 的ROOT日志记录级别（如果它没有任何其他祖先），即WARNING：

logger.setLevel(logging.DEBUG)

带输出的完整代码：

import logging

logger = logging.getLogger(__name__)

# Create handlers
c_handler = logging.StreamHandler()
f_handler = logging.FileHandler('file.log')
logger.setLevel(logging.DEBUG) # <<< Added Line
c_handler.setLevel(logging.DEBUG)
f_handler.setLevel(logging.INFO)

# Create formatters and add it to handlers
c_format = logging.Formatter('%(name)s - %(levelname)s - %(message)s')
f_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
c_handler.setFormatter(c_format)
f_handler.setFormatter(f_format)

# Add handlers to the logger
logger.addHandler(c_handler)
logger.addHandler(f_handler)


logger.warning('logs')
logger.error('logs')
logger.info('should log but doesn\'t')
logger.debug('should log but doesn\'t')

输出：

__main__ - WARNING - logs
__main__ - ERROR - logs
__main__ - INFO - should log but doesn't
__main__ - DEBUG - should log but doesn't