Get exception description and stack trace which caused an exception, all as a string

Question

I\'ve seen a lot of posts about stack trace and exceptions in Python. But haven\'t found what I need.

I have a chunk of Python 2.7 code that may raise an exception.

Answer 1

For those using Python-3

Using traceback module and exception.__traceback__ one can extract the stack-trace as follows:

• grab the current stack-trace using traceback.extract_stack()
• remove the last three elements (as those are entries in the stack that got me to my debug function)
• append the __traceback__ from the exception object using traceback.extract_tb()
• format the whole thing using traceback.format_list()

import traceback
def exception_to_string(excp):
   stack = traceback.extract_stack()[:-3] + traceback.extract_tb(excp.__traceback__)  # add limit=?? 
   pretty = traceback.format_list(stack)
   return ''.join(pretty) + '\n  {} {}'.format(excp.__class__,excp)

A simple demonstration:

def foo():
    try:
        something_invalid()
    except Exception as e:
        print(exception_to_string(e))

def bar():
    return foo()

We get the following output when we call bar():

  File "./test.py", line 57, in 
    bar()
  File "./test.py", line 55, in bar
    return foo()
  File "./test.py", line 50, in foo
    something_invalid()

   name 'something_invalid' is not defined