Exceptions do not properly pickle and unpickle

[amachanic]

Describe the bug

If an exception generated by mssql-python is pickled, the following error will occur on unpickle:
[error].__init__() missing 1 required positional argument: 'ddbc_error'

This causes issues when using e.g. multiprocessing and attempting to marshal errors back to a central process.

To reproduce

import mssql_python, pickle

conn = mssql_python.connect("conn_string_here")
cur = conn.cursor()
try:
    cur.execute('insert into fake_tbl values (123)')
except Exception as e:
    d = pickle.dumps(e)

ex = pickle.loads(d)

Expected behavior

The pickled exception should cleanly unpickle, and then I should be able to treat it just like any other exception object.

Further technical details

Python version: 3.12.3
SQL Server version: N/A
Operating system: N/A

[github-actions]

Hi Adam Machanic (@amachanic), thank you for opening this issue!

Our team will review it shortly. We aim to triage all new issues within 24-48 hours and get back to you.

If you have additional information to share, please feel free to update the issue.

Thank you for your patience!

[bewithgaurav]

Thanks for the report, Adam Machanic (@amachanic), confirmed the repro. The exception classes aren't round-tripping through pickle cleanly, which is why multiprocessing (and similar) chokes on them. We'll get a fix up shortly and link this PR.
Thanks again, will keep this posted.

[jahnvi480]

amachani, We have merged this PR and this will be available in our next release.
Thanks for raising the issue and helping us make our driver better. Keep trying our driver and share your feedback!