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Extensible exception handling middleware

Author:
kcarnold
Posted:
March 10, 2008
Language:
Python
Version:
.96
Tags:
middleware exception
Score:
3 (after 3 ratings)

This exception middleware abstracts the functionality of the builtin exception handling mechanisms, but makes them extensible by inheritance.

Just add it (or some subclass) to the top of your active middleware list.

You can use this to make your admin emails more informative or log errors to a file.

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from django.conf import settings
from django import http
from django.core.mail import mail_admins

import sys

# Temporary, from http://code.djangoproject.com/attachment/ticket/6094/6094.2008-02-01.diff
from django.core.urlresolvers import RegexURLResolver
def resolver(request):
    """
    Returns a RegexURLResolver for the request's urlconf.

    If the request does not have a urlconf object, then the default of
    settings.ROOT_URLCONF is used.
    """
    from django.conf import settings
    urlconf = getattr(request, "urlconf", settings.ROOT_URLCONF)
    return RegexURLResolver(r'^/', urlconf)


class StandardExceptionMiddleware(object):
    def process_exception(self, request, exception):
        # Get the exception info now, in case another exception is thrown later.
        if isinstance(exception, http.Http404):
            return self.handle_404(request, exception)
        else:
            return self.handle_500(request, exception)


    def handle_404(self, request, exception):
        if settings.DEBUG:
            from django.views import debug
            return debug.technical_404_response(request, exception)
        else:
            callback, param_dict = resolver(request).resolve404()
            return callback(request, **param_dict)


    def handle_500(self, request, exception):
        exc_info = sys.exc_info()
        if settings.DEBUG:
            return self.debug_500_response(request, exception, exc_info)
        else:
            self.log_exception(request, exception, exc_info)
            return self.production_500_response(request, exception, exc_info)


    def debug_500_response(self, request, exception, exc_info):
        from django.views import debug
        return debug.technical_500_response(request, *exc_info)


    def production_500_response(self, request, exception, exc_info):
        '''Return an HttpResponse that displays a friendly error message.'''
        callback, param_dict = resolver(request).resolve500()
        return callback(request, **param_dict)


    def exception_email(self, request, exc_info):
        subject = 'Error (%s IP): %s' % ((request.META.get('REMOTE_ADDR') in settings.INTERNAL_IPS and 'internal' or 'EXTERNAL'), request.path)
        try:
            request_repr = repr(request)
        except:
            request_repr = "Request repr() unavailable"
        message = "%s\n\n%s" % (_get_traceback(exc_info), request_repr)
        return subject, message


    def log_exception(self, request, exception, exc_info):
        subject, message = self.exception_email(request, exc_info)
        mail_admins(subject, message, fail_silently=True)



def _get_traceback(self, exc_info=None):
    """Helper function to return the traceback as a string"""
    import traceback
    return '\n'.join(traceback.format_exception(*(exc_info or sys.exc_info())))

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