BaseCommand --traceback should raise the original Exception

[jorgebastida]

When you are debugging long-running process that take hours to finish is really helpful to run them using ipython --pdb <script> so in case of failure, you'll get a ipdb trace just before the Exception was raised, so you can check what was wrong and fix it instead of adding an ipdb and re running the script.

As for the last weeks I've been writing some django command that takes hours to run I tried to run these scripts using ipython --pdb manage.py <command> but unfortunately I found that BaseCommand.run_from_argv was capturing any Exception raised by my command and printing the traceback to stderr if the --traceback option was present, or name and error if not.

In order to use ipython --pdb I need to override run_from_argv In my commands and basically don't try/except self.execute(*args, **options.__dict__) what is pretty hacky.

After talking with Russell Keith-Magee we found that, as python default behavior is to print the traceback into stderr}} and return an error status code when an Exception is raised and not captured, the solution would probably be to {{{raise the Exception if --traceback is present. The consequences are:

a) The existing behavior doesn't change.
b) We can call manage.py commands from interpreters that do fancy things when exceptions are raised.

I haven't found anything related in the "Better Error Message" wiki page: https://code.djangoproject.com/wiki/BetterErrorMessages

[jorgebastida]

Pull request available here ​https://github.com/django/django/pull/1137

[Claude Paroz]

This makes sense.

[Claude Paroz <claude@…>]

In 888c86dcf30defe533451bcefc6e09a6e181389f:

Fixed #20445 -- Raised original exception after command error