When I catch an exception, how do I get the type, file, and line number?

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Catching an exception that would print like this:

Traceback (most recent call last):
  File "c:/tmp.py", line 1, in <module>
    4 / 0
ZeroDivisionError: integer division or modulo by zero

I want to format it into:

ZeroDivisonError, tmp.py, 1
7 Answers

Without any imports, but also incompatible with imported modules:

try:
    raise TypeError("Hello, World!")  # line 2
except Exception as e:
    print(
        type(e).__name__,          # TypeError
        __file__,                  # /tmp/example.py
        e.__traceback__.tb_lineno  # 2
    )

$ python3 /tmp/example.py
TypeError /tmp/example.py 2

To reiterate, this does not work across imports or modules, so if you do import X; try: X.example(); then the filename and line number will point to the line containing X.example() instead of the line where it went wrong within X.example(). If anyone knows how to easily get the file name and line number from the last stack trace line (I expected something like e[-1].filename, but no such luck), please improve this answer.

You could achieve this without having to import traceback:

try:
    func1()
except Exception as ex:
    trace = []
    tb = ex.__traceback__
    while tb is not None:
        trace.append({
            "filename": tb.tb_frame.f_code.co_filename,
            "name": tb.tb_frame.f_code.co_name,
            "lineno": tb.tb_lineno
        })
        tb = tb.tb_next
    print(str({
        'type': type(ex).__name__,
        'message': str(ex),
        'trace': trace
    }))

Output:

{

  'type': 'ZeroDivisionError',
  'message': 'division by zero',
  'trace': [
    {
      'filename': '/var/playground/main.py',
      'name': '<module>',
      'lineno': 16
    },
    {
      'filename': '/var/playground/main.py',
      'name': 'func1',
      'lineno': 11
    },
    {
      'filename': '/var/playground/main.py',
      'name': 'func2',
      'lineno': 7
    },
    {
      'filename': '/var/playground/my.py',
      'name': 'test',
      'lineno': 2
    }
  ]
}

This is what I used to get the file name.

__file__.__str__

To sum it, I created a page to show errors. Return this on exception.

context={
                'details':'Type of error:{}:Function name:{}:Line number:{}'.format(exc_type, fname, exc_tb.tb_lineno),
                'error_details':str(e),
                'filename':__file__.__str__,
            })

How it looks in case an exception occurs:

enter image description here

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