如何配置python的日志记录模块以将格式化程序用于多行输出？

Question

我已将日志记录模块配置为使用以下格式格式化日志消息：

...
    'formatters': {
        'verbose': {
            'format': '%(asctime)s [%(levelname)s] '
                      '(%(name)s:pid=%(process)d) %(module)s(%(lineno)d): '
                      '%(message)s'
        },
    },
...

但是，当打印异常时，它显示为：

2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105): Catchall exception at top level.
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/argh/dispatching.py", line 228, in dispatch_command
    dispatch(parser, *args, **kwargs)
  File "build/bdist.linux-x86_64/egg/argh/dispatching.py", line 124, in dispatch
    for line in lines:
  File "build/bdist.linux-x86_64/egg/argh/dispatching.py", line 200, in _execute_command
    for line in result:
  ...,
NameError: global name 'sftp' is not defined

是否可以使其通过格式化程序运行每一行？ 例如，它将输出如下内容：

2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105): Catchall exception at top level.
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105): Traceback (most recent call last):
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):   File "build/bdist.linux-x86_64/egg/argh/dispatching.py", line 228, in dispatch_command
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):     dispatch(parser, *args, **kwargs)
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):   File "build/bdist.linux-x86_64/egg/argh/dispatching.py", line 124, in dispatch
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):     for line in lines:
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):   File "build/bdist.linux-x86_64/egg/argh/dispatching.py", line 200, in _execute_command
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):     for line in result:
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105):   ...,
2014-02-12 14:16:20,454 [ERROR] (app:pid=1930) main(105): NameError: global name 'sftp' is not defined

Answer 1

您无需配置即可执行此操作。 使用traceback.format_exec以字符串形式获取堆栈跟踪，然后拆分各行并分别记录每行。

import logging
import traceback

logger = logging.Logger(__name__) # or whatever namespace you so please
# do any other Logger configuration you want

try:
    do_some_stuff()
except Exception as e:
    for line in traceback.format_exec().split('\n'):
        logger.error(line)

但是，这不是常见的做法。 如果使用Logger.exception() ，则可以记录该异常。 它在一行日志记录中，但是会在多行Logger中写入Logger正在写入的类似文件的对象。

（有趣的是logging.Formatter类的方法formatException使用默认值traceback.print_exception 。）

Answer 2

我认为你可以使用json模块

import json

a = {"a": 1, "b": 2}

print json.dumps(a, indent=4)

输出：

{
    "a": 1, 
    "b": 2
}