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authorVinay Sajip <vinay_sajip@yahoo.co.uk>2015-01-28 07:32:38 (GMT)
committerVinay Sajip <vinay_sajip@yahoo.co.uk>2015-01-28 07:32:38 (GMT)
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Added a logging cookbook entry on customized exception formatting.
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@@ -2033,3 +2033,58 @@ A couple of extra points to note:
information on how logging supports using user-defined objects in its
configuration, and see the other cookbook recipe :ref:`custom-handlers` above.
+
+.. _custom-format-exception:
+
+Customized exception formatting
+-------------------------------
+
+There might be times when you want to do customized exception formatting - for
+argument's sake, let's say you want exactly one line per logged event, even
+when exception information is present. You can do this with a custom formatter
+class, as shown in the following example::
+
+ import logging
+
+ class OneLineExceptionFormatter(logging.Formatter):
+ def formatException(self, exc_info):
+ """
+ Format an exception so that it prints on a single line.
+ """
+ result = super(OneLineExceptionFormatter, self).formatException(exc_info)
+ return repr(result) # or format into one line however you want to
+
+ def format(self, record):
+ s = super(OneLineExceptionFormatter, self).format(record)
+ if record.exc_text:
+ s = s.replace('\n', '') + '|'
+ return s
+
+ def configure_logging():
+ fh = logging.FileHandler('output.txt', 'w')
+ f = OneLineExceptionFormatter('%(asctime)s|%(levelname)s|%(message)s|',
+ '%d/%m/%Y %H:%M:%S')
+ fh.setFormatter(f)
+ root = logging.getLogger()
+ root.setLevel(logging.DEBUG)
+ root.addHandler(fh)
+
+ def main():
+ configure_logging()
+ logging.info('Sample message')
+ try:
+ x = 1 / 0
+ except ZeroDivisionError as e:
+ logging.exception('ZeroDivisionError: %s', e)
+
+ if __name__ == '__main__':
+ main()
+
+When run, this produces a file with exactly two lines::
+
+ 28/01/2015 07:21:23|INFO|Sample message|
+ 28/01/2015 07:21:23|ERROR|ZeroDivisionError: integer division or modulo by zero|'Traceback (most recent call last):\n File "logtest7.py", line 30, in main\n x = 1 / 0\nZeroDivisionError: integer division or modulo by zero'|
+
+While the above treatment is simplistic, it points the way to how exception
+information can be formatted to your liking. The :mod:`traceback` module may be
+helpful for more specialized needs.