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python exception message capturing

Posted by: admin November 1, 2017 Leave a comment

Questions:
import ftplib
import urllib2
import os
import logging
logger = logging.getLogger('ftpuploader')
hdlr = logging.FileHandler('ftplog.log')
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
hdlr.setFormatter(formatter)
logger.addHandler(hdlr)
logger.setLevel(logging.INFO)
FTPADDR = "some ftp address"

def upload_to_ftp(con, filepath):
    try:
        f = open(filepath,'rb')                # file to send
        con.storbinary('STOR '+ filepath, f)         # Send the file
        f.close()                                # Close file and FTP
        logger.info('File successfully uploaded to '+ FTPADDR)
    except, e:
        logger.error('Failed to upload to ftp: '+ str(e))

This doesn’t seem to work, I get syntax error, what is the proper way of doing this for logging all kind of exceptions to a file

Answers:

You have to define which type of exception you want to catch. So write except Exception, e: instead of except, e: for a general exception (that will be logged anyway).

Other possibility is to write your whole try/except code this way:

try:
    with open(filepath,'rb') as f:
        con.storbinary('STOR '+ filepath, f)
    logger.info('File successfully uploaded to '+ FTPADDR)
except Exception, e:
    logger.error('Failed to upload to ftp: '+ str(e))

Questions:
Answers:

The syntax is no longer supported in python 3. Use the following instead.

try:
    do_something()
except BaseException as e:
    logger.error('Failed to do something: ' + str(e))

Questions:
Answers:

Updating this to something simpler for logger (works for both python 2 and 3). You do not need traceback module.

import logging

logger = logging.Logger('catch_all')

def catchEverythingInLog():
    try:
        ... do something ...
    except Exception as e:
        logger.error(e, exc_info=True)
        ... exception handling ...

This is now the old way (though still works):

import sys, traceback

def catchEverything():
    try:
        ... some operation(s) ...
    except:
        exc_type, exc_value, exc_traceback = sys.exc_info()
        ... exception handling ...

exc_value is the error message.

Questions:
Answers:

You can use logger.exception("msg") for logging exception with traceback:

try:
    #your code
except Exception as e:
    logger.exception('Failed: ' + str(e))

Questions:
Answers:

You can use the e.message or e.messages

try:
  ...
except Exception as e:
  print(e.message)

Questions:
Answers:

You can try specifying the BaseException type explicitly. However, this will only catch derivatives of BaseException. While this includes all implementation-provided exceptions, it is also possibly to raise arbitrary old-style classes.

try:
  do_something()
except BaseException, e:
  logger.error('Failed to do something: ' + str(e))