Extra fields for logging

[Steven D'Aprano]

On Fri, 25 Dec 2009 12:07:20 -0800, Joan Miller wrote:

> On 25 dic, 13:24, Steven D'Aprano <st... at REMOVE-THIS-
> cybersource.com.au> wrote:
>> On Thu, 24 Dec 2009 05:06:48 -0800, Joan Miller wrote:
>> > I'm trying to add some extra fields to logging, I'm following this
>> > information [1] but it faills in my case.
>> [...]
>> > I get => KeyError: 'host'
>>
>> Please post the entire traceback you get.
>>
>> --
>> Steven
> 
> Traceback (most recent call last):
>   File "/usr/lib/python2.6/logging/__init__.py", line 768, in emit
>     msg = self.format(record)
>   File "/usr/lib/python2.6/logging/__init__.py", line 648, in format
>     return fmt.format(record)
>   File "/usr/lib/python2.6/logging/__init__.py", line 439, in format
>     s = self._fmt % record.__dict__
> KeyError: 'host'


Hmmm... that wasn't as helpful as I had hoped. Oh well.

Going back to your earlier post, I can see a couple of problems.

Firstly, your __getitem__ method always returns None. You need to return 
the result.

Secondly, this works for me:


import logging
class ExtraInfo(object):
    def __getitem__(self, name):
        if name == 'host':
            result = 'foo'
        return result
    def __iter__(self):
        keys = ['host',]
        keys.extend(self.__dict__.keys())
        return iter(keys)  # better than keys.__iter__

def setup(filename='/tmp/foo.log'):
    log = logging.LoggerAdapter(logging.getLogger('foo'), ExtraInfo())
    logging.basicConfig(
        level=logging.DEBUG,
        format="""Date-Time: %(asctime)s
Host: %(host)s
%(levelname)s:
%(message)s""",
    datefmt="%Y-%m-%dT%H:%M:%S%z",
    filename=filename,
    filemode='w')
    return log

log = setup()
log.error('testing ...')
log.debug('something happened')
log.critical("it's the end of the world as we know it!")





Hope this helps.


-- 
Steven