SlackApiError cannot be unpickled

SlackApiError raises an error when trying to unpickle it.

This is particularly annoying in a Celery task since another bug in celery will cause the whole worker node to fail.

The Slack SDK version

2.9.4

Python runtime version

3.11.0

OS info

ProductName: macOS
ProductVersion: 13.0
BuildVersion: 22A380
Darwin Kernel Version 22.1.0: Sun Oct 9 20:15:09 PDT 2022; root:xnu-8792.41.9~2/RELEASE_ARM64_T6000

Steps to reproduce:

import pickle
from slack.errors import SlackApiError

e = SlackApiError("Internal server error", "<response>")

dumped = pickle.dumps(e)
pickle.loads(dumped) 

Expected result:

No error.

Actual result:

Traceback (most recent call last):
  File "/private/tmp/pickle_exc/bug.py", line 7, in <module>
    pickle.loads(dumped)
TypeError: SlackApiError.__init__() missing 1 required positional argument: 'response'

Solution

The SlackApiError could be implemented in such a way that the constructor accepts only the message, and the response defaults to None. Then the string representation can be delegated to __str__:

class SlackApiError(Exception):

    def __init__(self, message, response=None):
        super().__init__(message)
        self.response = response
    
    def __str__(self):
        return f"{self.args[0]}\nThe server responded with: {self.response}"

从 SlackApiError 的定义开始，在 Python 3.11 上运行 issue 中所示的 pickle 复现。检查异常的初始化和表示方式，然后验证 pickling 和 unpickling 能够保留消息和响应，且不会引发 TypeError。