How do you log a manually raised exception in an if statement in python

Question

Put simply, I have a piece of code that looks like this:

if some_condition_that_evals_to_True:
    raise ValueError("Error message")

What I want to do is to insert a logging statement that logs this entire exception but doing it just this way only saves the logger message:

if some_condition_that_evals_to_True:
    logger.error("Logged error message")
    raise ValueError("Error message")

Any one know how to save the entire error message including the ValueError?

EDIT:

The following is what I am trying to recreate:

if some_condition_that_evals_to_True:
    try:
        raise ValueError("Error with value")
    except ValueError:
        logger.exception("Logging Error with Value")
        raise 

But this seems like a roundabout way to get the behavior I want, so another way to phrase my question: Is there a more elegant way get the same behavior as the above codeblock?

Answer 1

Try the stack_info keyword argument when using the logging module:

import logging
logging.basicConfig(filename='example.log',level=logging.DEBUG)
if True:
    logging.error('Error Message', stack_info=True)
    raise ValueError('Custom Error Message')

Running this shows the following:

J:\>python log_stack.py
Traceback (most recent call last):
  File "log_stack.py", line 5, in <module>
    raise ValueError('Custom Error Message')
ValueError: Custom Error Message

J:\>more example.log
ERROR:root:Error Message
Stack (most recent call last):
  File "log_stack.py", line 4, in <module>
    logging.error('Error Message', stack_info=True)