Customize the uncaught exception error message so it JSON

[dilzeem]

Hi I have this custom sink that I use to handle exceptions

def log_exception(*args):
    if len(args) == 1:
        e = args[0]
        etype, value, tb = type(e), e, e.__traceback__
    elif len(args) == 3:
        etype, value, tb = args
    else:
        logger.error("Not able to log exception. Wrong number of arguments given. Should either receive 1 argument "
                        "- an exception, or 3 arguments: exc type, exc value and traceback")
        return

    tb_parsed = []
    for filename, lineno, func, text in traceback.extract_tb(tb):
        tb_parsed.append({"filename": filename, "lineno": lineno, "func": func, "text": text})

    logger.exception(
        "Uncaught exception", extra={
            "exception": traceback.format_exception_only(etype, value)[0].strip(),
            "traceback": tb_parsed
        }
    )

logger.remove()
logger.add(sys.stdout, serialize=True, level="INFO")
sys.excepthook = log_exception

It works fine, and catches the error and formats except the error message, but it is not exactly JSON because of the text Record was: . Is there a way to format this logging error or remove that text so that line is JSON as well?

--- Logging error in Loguru Handler #1 ---
Record was: {'elapsed': datetime.timedelta(seconds=1, microseconds=314659), 'exception': (type=None, value=None, traceback=None), 'extra': {'extra': {'exception': "KeyError: 'yes'", 'traceback': [{'filename': '/mnt/c/Users/sivaharan.rajkumar/GoogleDrive/projects/aws_debug/aws_debug/main.py', 'lineno': 39, 'func': '<module>', 'text': "print(some_dict['yes'])"}]}}, 'file': (name='init_logging.py', path='/mnt/c/Users/sivaharan.rajkumar/GoogleDrive/projects/aws_debug/aws_debug/init_logging.py'), 'function': 'log_exception', 'level': (name='ERROR', no=40, icon='❌'), 'line': 26, 'message': 'Uncaught exception', 'module': 'init_logging', 'name': 'init_logging', 'process': (id=6496, name='MainProcess'), 'thread': (id=140600093005632, name='MainThread'), 'time': datetime(2020, 7, 15, 20, 37, 34, 180836, tzinfo=datetime.timezone(datetime.timedelta(seconds=7200), 'CEST'))}
Traceback (most recent call last):
  File "/home/dilzeem/.cache/pypoetry/virtualenvs/aws-debug-ivZo2Zzb-py3.7/lib/python3.7/site-packages/loguru/_handler.py", line 165, in emit
    formatted = self._serialize_record(formatted, record)
  File "/home/dilzeem/.cache/pypoetry/virtualenvs/aws-debug-ivZo2Zzb-py3.7/lib/python3.7/site-packages/loguru/_handler.py", line 231, in _serialize_record
    "type": record["exception"].type.__name__,
AttributeError: 'NoneType' object has no attribute '__name__'
--- End of logging error ---

[Delgan]

Hey @dilzeem, actually you just discovered a bug!

The error you're seeing comes from the internals of loguru. It's there to explain that something went wrong: while trying to serialize the log message, an unexpected error occurred because the logger tried to access attribute from an object which is None. It happens because logger.exception() is called outside of the try / except block.

I will fix that for the next release. In the meantime, I suggest you to replace logger.exception() with logger.error() or logger.opt(exception=args).error(). 😉

[dilzeem]

Hi @Delgan

Thanks for the prompt response, and an awesome library.
Made the changes as suggested, and it worked like a charm :)

[Delgan]

Fixed on master. 👍