前言
線上的程式報錯的時候，使用 python 的標準庫 logging 記錄的日誌 debug 問題，是我們常用的操作，但是 logging 沒有直接提供給我們列印變數值的功能，這個需要我們顯性的寫在日誌中,就像這樣： logger.debug(f'error: {a}')
但是錯誤是一個鏈條，不是一個點，如果在每處都加上列印語句的話，工作量太大了
python 的第三方日誌庫 loguru ，可以很好的幫助我們實現這個需求
效果展示
你想要實現下面的效果嗎？
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()
│ └ <function Thread._bootstrap_inner at 0x10556dc10>
└ <Thread(ThreadPoolExecutor-0_14, started 6343241728)>
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 973, in _bootstrap_inner
self.run()
│ └ <function Thread.run at 0x10556d940>
└ <Thread(ThreadPoolExecutor-0_14, started 6343241728)>
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 910, in run
self._target(*self._args, **self._kwargs)
│ │ │ │ │ └ {}
│ │ │ │ └ <Thread(ThreadPoolExecutor-0_14, started 6343241728)>
│ │ │ └ (<weakref at 0x106459450; to 'ThreadPoolExecutor' at 0x105fafd30>, <_queue.SimpleQueue object at 0x1053e88b0>, None, ())
│ │ └ <Thread(ThreadPoolExecutor-0_14, started 6343241728)>
│ └ <function _worker at 0x105fd6d30>
└ <Thread(ThreadPoolExecutor-0_14, started 6343241728)>
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/concurrent/futures/thread.py", line 77, in _worker
work_item.run()
│ └ <function _WorkItem.run at 0x105fd6e50>
└ <concurrent.futures.thread._WorkItem object at 0x106fbb4c0>
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)
│ │ │ │ │ └ {}
│ │ │ │ └ <concurrent.futures.thread._WorkItem object at 0x106fbb4c0>
│ │ │ └ ()
│ │ └ <concurrent.futures.thread._WorkItem object at 0x106fbb4c0>
│ └ <function func at 0x104e58040>
└ <concurrent.futures.thread._WorkItem object at 0x106fbb4c0>
> 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
│ └ <function Response.json at 0x105fb40d0>
└ <Response [500]>
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)
│ │ │ │ └ {}
│ │ │ └ <property object at 0x105fb24f0>
│ │ └ <Response [500]>
│ └ <function loads at 0x105c58a60>
└ <module 'json' from '/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/__init__.py'>
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/__init__.py", line 346, in loads
return _default_decoder.decode(s)
│ │ └ '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n<title>500 Internal Server Error</title>\n<h1>Internal Server Error...
│ └ <function JSONDecoder.decode at 0x105c583a0>
└ <json.decoder.JSONDecoder object at 0x105c50130>
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())
│ │ │ │ └ '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n<title>500 Internal Server Error</title>\n<h1>Internal Server Error...
│ │ │ └ <built-in method match of re.Pattern object at 0x105c493f0>
│ │ └ '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n<title>500 Internal Server Error</title>\n<h1>Internal Server Error...
│ └ <function JSONDecoder.raw_decode at 0x105c58430>
└ <json.decoder.JSONDecoder object at 0x105c50130>
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
│ └ '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n<title>500 Internal Server Error</title>\n<h1>Internal Server Error...
└ <class 'json.decoder.JSONDecodeError'>
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
一個簡單的例子
使用 loguru 吧！
loguru 提供了 exception 方法來列印異常logger.exception() 需要一個引數，隨便填什麼都可以，我習慣用 error
logger.exception和logger.error不一樣。前者會做變數跟蹤，但是後者不會
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__:<module>:11 - division by zero
Traceback (most recent call last):
> File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 9, in <module>
func(0, 0)
└ <function func at 0x104a4c040>
File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 5, in func
a/b
│ └ 0
└ 0
ZeroDivisionError: division by zero從圖中可以看到，日誌展示時候，列印了變數 a 和 b 的值
鏈式異常
loguru 對鏈式異常(raise ... from ...)的支援也很好
如果你不知道什麼是異常鏈，可以看 Python 官方文件——異常鏈
from loguru import logger
def func(a: int, b: int):
try:
a/b
except Exception as error:
raise Exception('計算錯誤') 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__:<module>:14 - 計算錯誤
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 <module>
func(0, 0)
└ <function func at 0x1046e0040>
File "/Users/bot/Desktop/code/ideaboom/test_logger/003.py", line 8, in func
raise Exception('計算錯誤') from error
└ Exception('計算錯誤')
Exception: 計算錯誤