Pretty and more helpful exceptions in Python, automatically.
better_exceptions via pip:
$ pip install better_exceptions
And set the
BETTER_EXCEPTIONS environment variable to any value:
export BETTER_EXCEPTIONS=1 # Linux / OSX setx BETTER_EXCEPTIONS 1 # Windows
Python REPL (Interactive Shell)
In order to use
better_exceptions in the Python REPL, first install the package (as instructed above) and run:
$ python -m better_exceptions Type "help", "copyright", "credits" or "license" for more information. (BetterExceptionsConsole) >>>
in order to drop into a
better_exceptions-enabled Python interactive shell.
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
better_exceptions in production, do not forget to unset the
BETTER_EXCEPTIONS variable to avoid leaking sensitive data in your logs.
Use with unittest
If you want to use
better_exceptions to format
unittest's exception output, you can use the monkey patch below:
import sys import unittest import better_exceptions def patch(self, err, test): lines = better_exceptions.format_exception(*err) if sys.version_info == 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.
Tested with Django 1.11
Create a middleware exception handler in a file like
import sys from better_exceptions import excepthook class BetterExceptionsMiddleware(object): def __init__(self, get_response): self.get_response = get_response def __call__(self, request): return self.get_response(request) def process_exception(self, request, exception): excepthook(exception.__class__, exception, sys.exc_info()) return None
settings.py, add your new class to the
MIDDLEWARE = [ ... 'myapp.middleware.BetterExceptionsMiddleware', ]
If you do not see beautiful exceptions, first make sure that the environment variable does exist. You can try
echo $BETTER_EXCEPTIONS (Linux / OSX) or
echo %BETTER_EXCEPTIONS% (Windows). On Linux and OSX, the
export command does not add the variable permanently, you will probably need to edit the
~/.profile file to make it persistent. On Windows, you need to open a new terminal after the
Check that there is no conflict with another library, and that the
sys.excepthook function has been correctly replaced with the
better_exceptions's one. Sometimes other components can set up their own exception handlers, such as the
python3-apport Ubuntu package that you may need to uninstall.
Make sure that you have not inadvertently deleted the
better_exceptions_hook.pth file that should be in the same place as the
better_exceptions folder where all of your Python packages are installed. Otherwise, try re-installing
You can also try to manually activate the hook by adding
import better_exceptions; better_exceptions.hook() at the beginning of your script.
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 versions, OS, code snippet, interpeter, etc.) so that we can reproduce the bug you are experiencing.
Copyright © 2017, Josh Junon. Licensed under the MIT license.