前言
线上的程序报错的时候，使用 python 的标准库 logging 记录的日志 debug 问题，是我们常用的操作，但是 logging 没有直接提供给我们打印变量值的功能，这个需要我们显性的写在日志中,就像这样： logger.debug(f'error: {a}')
但是错误是一个链条，不是一个点，如果在每处都加上打印语句的话，工作量太大了
python 的第三方日志库 loguru ，可以很好的帮助我们实现这个需求
效果展示
你想要实现下面的效果吗？
2022-01-09 15:59:52.058 | ERROR | __main__:func:32 - Expecting value: line 1 column 1 (char 0)
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 930, in _bootstrap
self._bootstrap_inner()
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 973, in _bootstrap_inner
self.run()
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 910, in run
self._target(*self._args, **self._kwargs)
│ │ │ │ │ └ {}
│ │ │ │ └
│ │ │ └ (, <_queue.SimpleQueue object at 0x1053e88b0>, None, ())
│ │ └
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/concurrent/futures/thread.py", line 77, in _worker
work_item.run()
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/concurrent/futures/thread.py", line 52, in run
result = self.fn(*self.args, **self.kwargs)
│ │ │ │ │ └ {}
│ │ │ │ └
│ │ │ └ ()
│ │ └
│ └
└
> File "/Users/bot/Desktop/code/ideaboom/test_zjwt/test_api_copy.py", line 27, in func
assert int(response.json().get('r')) == (a+b)
│ │ │ └ 54
│ │ └ 100
│ └
└
File "/Users/bot/.local/share/virtualenvs/ideaboom-8ZWsq-JB/lib/python3.9/site-packages/requests/models.py", line 910, in json
return complexjson.loads(self.text, **kwargs)
│ │ │ │ └ {}
│ │ │ └
│ │ └
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/__init__.py", line 346, in loads
return _default_decoder.decode(s)
│ │ └ '\n500 Internal Server Error \nInternal Server Error...
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 337, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
│ │ │ │ └ '\n500 Internal Server Error \nInternal Server Error...
│ │ │ └
│ │ └ '\n500 Internal Server Error \nInternal Server Error...
│ └
└
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 355, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
│ └ '\n500 Internal Server Error \nInternal Server Error...
└
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
一个简单的例子
使用 loguru 吧！
loguru 提供了 exception 方法来打印异常logger.exception() 需要一个参数，随便填什么都可以，我习惯用 error
logger.exception和logger.error不一样。前者会做变量跟踪，但是后者不会
效果展示：
from loguru import logger
def func(a: int, b: int):
a/b
try:
func(0, 0)
except Exception as error:
logger.exception(error)
─➤ python -u "/Users/bot/Desktop/code/ideaboom/test_logger/003.py"
2022-01-09 23:44:12.792 | ERROR | __main__::11 - division by zero
Traceback (most recent call last):
> File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 9, in
func(0, 0)
└
File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 5, in func
a/b
│ └ 0
└ 0
ZeroDivisionError: division by zero 从图中可以看到，日志展示时候，打印了变量 a 和 b 的值
链式异常
loguru 对链式异常的支持也很好
如果你不知道什么是异常链，可以看 Python 官方文档——异常链
from loguru import logger
def func(a: int, b: int):
try:
a/b
except Exception as error:
raise Exception('计算错误') from error
try:
func(0, 0)
except Exception as error:
logger.exception(error)
─➤ python -u "/Users/bot/Desktop/code/ideaboom/test_logger/003.py"
2022-01-09 23:43:04.729 | ERROR | __main__::14 - 计算错误
Traceback (most recent call last):
File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 6, in func
a/b
│ └ 0
└ 0
ZeroDivisionError: division by zero
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
> File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 12, in
func(0, 0)
└
File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 8, in func
raise Exception('计算错误') from error
└ Exception('计算错误')
Exception: 计算错误 