better-exceptions

Pretty and more helpful exceptions in Python, automatically.

Usage

Install

better_exceptions

$ pip install better_exceptions

And set the

BETTER_EXCEPTIONS

export BETTER_EXCEPTIONS=1  # Linux / OSX
setx BETTER_EXCEPTIONS 1    # Windows

That's it!

Python REPL (Interactive Shell)

In order to use

better_exceptions

$ python -m better_exceptions
Type "help", "copyright", "credits" or "license" for more information.
(BetterExceptionsConsole)
>>>

in order to drop into a

better_exceptions

Advanced Usage

If you want to allow the entirety of values to be outputted instead of being truncated to a certain amount of characters:

import better_exceptions
better_exceptions.MAX_LENGTH = None

While using

better_exceptions

BETTER_EXCEPTIONS

Use with unittest

If you want to use

better_exceptions

unittest

import sys
import unittest
import better_exceptions

def patch(self, err, test):
    lines = better_exceptions.format_exception(*err)
    if sys.version_info[0] == 2:
        return u"".join(lines).encode("utf-8")
    return "".join(lines)
unittest.result.TestResult._exc_info_to_string = patch

Note that this uses an undocumented method override, so it is not guaranteed to work on all platforms or versions of Python.

Django Usage

In

settings.py

MIDDLEWARE

# ...

MIDDLEWARE = [
    # ...
    "better_exceptions.integrations.django.BetterExceptionsMiddleware",
]
...
from better_exceptions.integrations.django import skip_errors_filter
if you don't want to override LOGGING because you want to change the default,
you can vendor Django's default logging configuration and update it for
better-exceptions. the default for Django 3.1.4 can be found here:
https://github.com/django/django/blob/3.1.4/django/utils/log.py#L13-L63
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'filters': {
        'skip_errors': {
            '()': 'django.utils.log.CallbackFilter',
            'callback': skip_errors_filter,
        }
    },
    'handlers': {
        'console': {
            'level': 'INFO',
            # without the 'filters' key, Django will log errors twice:
            # one time from better-exceptions and one time from Django.
            # with the 'skip_errors' filter, we remove the repeat log
            # from Django, which is unformatted.
            'filters': ['skip_errors'],
            'class': 'logging.StreamHandler',
        }
    },
    'loggers': {
        'django': {
            'handlers': [
                'console',
            ],
        }
    }
}

example output:

Troubleshooting

If you do not see beautiful exceptions, first make sure that the environment variable does exist. You can try

echo $BETTER_EXCEPTIONS

echo %BETTER_EXCEPTIONS%

export

~/.profile

setx

Check that there is no conflict with another library, and that the

sys.excepthook

better_exceptions

python3-apport

Make sure that you have not inadvertently deleted the

better_exceptions_hook.pth

better_exceptions

better_exceptions

You can also try to manually activate the hook by adding

import better_exceptions; better_exceptions.hook()

Finally, if you still can not get this module to work, open a new issue by describing your problem precisely and detailing your configuration (Python and

better_exceptions

License

Copyright © 2017, Josh Junon. Licensed under the MIT license.