python 使用 loguru 输出异常日志同时打印变量值 python

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) ││││└ {} │││└ 【python 使用 loguru 输出异常日志同时打印变量值】││└ │└ └ 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 - 锐客网\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 - 锐客网\nInternal Server Error... │││└ ││└ '\n500 Internal Server Error - 锐客网\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 - 锐客网\nInternal Server Error... └ json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

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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 loggerdef func(a: int, b: int): a/btry: 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 └ 0ZeroDivisionError: 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

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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 loggerdef func(a: int, b: int): try: a/b except Exception as error: raise Exception('计算错误') from errortry: 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 └ 0ZeroDivisionError: division by zeroThe 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