Extra fields for logging

[Joan Miller]

On 26 dic, 04:34, Steven D'Aprano <st... at REMOVE-THIS-
cybersource.com.au> wrote:
> 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

Thanks Steven! You give me the idea.

* In the setup(), is not necessary to use:

    log = logging.LoggerAdapter(logging.getLogger('foo'), ExtraInfo()

neither return a value:

    return log

* The problem is that I'm using the logger at module-level so I had in
each module:

    logger = logging.getLogger(__name__)

but there is to use:

    logger = logging.LoggerAdapter(
        logging.getLogger(__name__), log.ExtraInfo())