BaseCommand.execute() swallows ImportError, CommandError even when --traceback is used

[charles@…]

Any ImportError or CommandError happening during BaseCommand.execute() is emitted as a single-line exception, even if --traceback is used. This can make exceptions caused by import loops difficult to debug.

--traceback should be honored, emitting full stack traces.

[Aymeric Augustin]

Could you provide a snippet to help us reproduce this problem?

[anonymous]

The easy-to-reproduce case is raising a CommandError from anywhere in execution:

from django.core.management.base import BaseCommand, CommandError

class Command(BaseCommand):
    """Trigger an ImportError with no stack trace even when --traceback is used"""

    help = 'Demonstrate #16397'

    def handle(self, *arguments, **options):
        raise CommandError('foo')

...in this case, running the command, even with --traceback, simply results in a single line of output: Error: foo.

However, this isn't much of a bug -- CommandErrors don't tend to happen anywhere but in management commands, and handling them in a user-friendly way tends to be desired behavior (though I think it might be fair to break that rule when --traceback is in use).

The much more interesting case is triggering an ImportError during translation.activate() -- this is what was biting me in practice. However, reproducing it (with the various bugs in my codebase which lead to it happening in practice fixed) appears to be nontrivial. I'll revisit this later.

[Aymeric Augustin]

#11667 was closed as a duplicate, check the discussions and patches over there before committing a fix for this ticket.

#17369 was also closed as a duplicate.

[Aymeric Augustin]

In [17197]:

Fixed #16397 -- Respected the --traceback flag in BaseCommand. This should make import loops easier to debug. Refs #11667, #17369.