Getting the exception value in Python

Question

If I have that code   try      some method   except Exception  e    How can I get this Exception value  string  representation I mean

User · Answer

Use repr   and The difference between using repr and str   Using repr    gt  gt  gt  try          print x      except Exception as e          print repr e        NameError  name  x  is not defined     Using str    gt  gt  gt  try          print x      except Exception as e          print str e        name  x  is not defined

User · Answer

For python2  It s better to use e message to get the exception message  this will avoid possible UnicodeDecodeError  But yes e message will be empty for some kind of exceptions like OSError  in which case we can add a exc info True to our logging function to not miss the error  For python3  I think it s safe to use str e

User · Answer

To inspect the error message and do something with it  with Python 3      try      some method   except Exception as e      if  value  in e args           do something

User · Answer

Even though I realise this is an old question  I d like to suggest using the traceback module to handle output of the exceptions   Use traceback print exc   to print the current exception to standard error  just like it would be printed if it remained uncaught  or traceback format exc   to get the same output as a string  You can pass various arguments to either of those functions if you want to limit the output  or redirect the printing to a file-like object

User · Answer

use str  try      some method   except Exception as e      s   str e    Also  most exception classes will have an args attribute  Often  args 0  will be an error message   It should be noted that just using str will return an empty string if there s no error message whereas using repr as pyfunc recommends will at least display the class of the exception  My take is that if you re printing it out  it s for an end user that doesn t care what the class is and just wants an error message   It really depends on the class of exception that you are dealing with and how it is instantiated  Did you have something in particular in mind

User · Answer

If you don t know the type origin of the error  you can try   import sys try      doSomethingWrongHere   except      print  Error      format sys exc info   0      But be aware  you ll get pep8 warning    W  PEP 8  E722   do not use bare except

User · Answer

Another way hasn t been given yet   try      1 0 except Exception  e      print e message   Output   integer division or modulo by zero   args 0  might actually not be a message   str e  might return the string with surrounding quotes and possibly with the leading u if unicode    integer division or modulo by zero    repr e  gives the full exception representation which is not probably what you want    ZeroDivisionError  integer division or modulo by zero       edit  My bad     It seems that BaseException message has been deprecated from 2 6  finally  it definitely seems that there is still not a standardized way to display exception messages  So I guess the best is to do deal with e args and str e  depending on your needs  and possibly e message if the lib you are using is relying on that mechanism    For instance  with pygraphviz  e message is the only way to display correctly the exception  using str e  will surround the message with u     But with MySQLdb  the proper way to retrieve the message is e args 1   e message is empty  and str e  will display   ERR CODE   ERR MSG

[python] Getting the exception value in Python

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