StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
text
Body
copied!<p>As said before you can use the logger module. You can set a default level of logging (for example Warning) and put all kind of messages in you code, since debug until critical. As humble explanation, if you set your logging level as Warning, even if your code log debug messages they will not appear in the file (or stdout). That's because the logging module will log only messages with priority higher or equal to Warning (Warning, Error and critical). </p> <p>As a simple explanation look at this code:</p> <pre><code>import logging import logging.handlers as handlers logger = logging.getLogger('myapp') hdlr = logging.FileHandler('/tmp/myapp.log') formatter = logging.Formatter('%(asctime)s %(levelname)s: %(message)s') hdlr.setFormatter(formatter) logger.addHandler(hdlr) logger.setLevel(logging.WARNING) logger.debug('debug!') logger.info('info!') logger.warning('warning!') logger.error('error!') logger.critical('critical!') </code></pre> <p>It creates a file called myapp.log:</p> <pre><code>magun@~: cat /tmp/myapp.log 2010-11-05 12:27:25,359 WARNING: warning! 2010-11-05 12:27:25,362 ERROR: error! 2010-11-05 12:27:26,071 CRITICAL: critical! magun@~: </code></pre> <p>If you're worried about the file size you can use a rotating log, witch will discard the oldest logs based in your criteria:</p> <pre><code>import logging import logging.handlers as handlers logger = logging.getLogger('myapp') hdlr = handlers.RotatingFileHandler('/tmp/log/myapp.log', maxBytes=100, backupCount=5) formatter = logging.Formatter('%(asctime)s %(levelname)s: %(message)s') hdlr.setFormatter(formatter) logger.addHandler(hdlr) logger.setLevel(logging.WARNING) for i in range(20): logger.debug('debug%i!'%i) logger.info('info%i!'%i) logger.warning('warning%i!'%i) logger.error('error%i!'%i) logger.critical('critical%i!'%i) </code></pre> <p>In this case I used a log file with a max size of 100 bytes (pretty small, you should raise it) and a backup count of 5. This means when a log reaches 100bytes it will be "rotated": a new (and empty) myapp.log will created and the old one will become myapp.log.1. In the next rotation myapp.log.1 will become myapp.log.2, the myapp.log will be come the new myapp.log.1. It will repeat until we have myapp.log, myapp.log.1, myapp.log.2, ... myapp.log.n (in this example the limit will be myapp.log.5). When we hit this the, and log need to be rotated, the myapp.log.5 file will be discarded. So, the size limit if 5*100bytes. </p> <p>Take a look of what happened:</p> <pre><code>magun@~: ls /tmp/log/ myapp.log myapp.log.1 myapp.log.2 myapp.log.3 myapp.log.4 myapp.log.5 magun@~: cat /tmp/log/myapp.log 2010-11-05 12:33:52,369 ERROR: error19! 2010-11-05 12:33:52,376 CRITICAL: critical19! magun@~: cat /tmp/log/myapp.log.1 2010-11-05 12:33:52,362 CRITICAL: critical18! 2010-11-05 12:33:52,369 WARNING: warning19! magun@~: cat /tmp/log/myapp.log.2 2010-11-05 12:33:52,355 WARNING: warning18! 2010-11-05 12:33:52,362 ERROR: error18! magun@~: cat /tmp/log/myapp.log.3 2010-11-05 12:33:52,348 ERROR: error17! 2010-11-05 12:33:52,355 CRITICAL: critical17! magun@~: cat /tmp/log/myapp.log.4 2010-11-05 12:33:52,340 CRITICAL: critical16! 2010-11-05 12:33:52,348 WARNING: warning17! magun@~: cat /tmp/log/myapp.log.5 2010-11-05 12:33:52,333 WARNING: warning16! 2010-11-05 12:33:52,340 ERROR: error16! magun@~: </code></pre> <p>As you can see we lost many logs (0-15), but the most recent are there, preserving the user free space. Don't forget to read the log from bottom up:)</p>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload