call_command() fails when required mutually exclusive arguments use the same `dest`.

[Peter Law]

I have a command which accepts two different ways to specify a time -- either as a timestamp or as a duration in the future:

pause (--for duration | --until time)

class Command(BaseCommand):
    def add_arguments(self, parser) -> None:
        group = parser.add_mutually_exclusive_group(required=True)
        group.add_argument('--for', dest='until', action='store', type=parse_duration_to_time)
        group.add_argument('--until', action='store', type=parse_time)

    def handle(self, until: datetime, **_):
        pass

This works fine on the command line, however there doesn't seem to be a way to make this work through call_command. Specifically there are two sides to the failure:

• while I can provide an until value (as a string, which is processed by parse_time) there is no mechanism to pass a for value if that's how I want to spell the input
• the for value is always required and attempts to parse the (string) until value passed, which then errors since the input formats are very different

[Mariusz Felisiak]

Thanks for the report. The following calls work as expected for me :

management.call_command('pause', '--until=1')
management.call_command('pause', '--until', '1')
management.call_command('pause', '--for=1')
management.call_command('pause', '--for', '1')

however I confirmed an issue when passing arguments in keyword arguments:

management.call_command('pause', until='1')
management.call_command('pause', **{'for': '1'}) # Using "call_command('pause', for='1')" raises SyntaxError

This is caused by using dest for mapping **options to arguments, see ​call_command().

[Hasan Ramezani]

I can create a patch to fix the two above-mentioned issues but using the command with both options together:

management.call_command('pause', **{'for': '1', 'util': '1'})

won't raise an error because both options use the same dest. I will investigate it more.

I don't know do we have to support passing both dest and arg name as keyword arguments? in the example of this ticket, if we call management.call_command('pause', until='1'), it should be considered as until arg or for (because dest of for is until as well)

[Peter Law]

Ah, interesting, I wasn't aware that those other spellings worked! I'd be happy to switch to using those spellings instead (I've confirmed they work for my original case).

Perhaps just documenting this limitation (and the fact that those spellings work as alternatives) and/or improving the related error messages could be a way to go here?

[Mariusz Felisiak]

Replying to Hasan Ramezani:

I don't know do we have to support passing both dest and arg name as keyword arguments? in the example of this ticket, if we call management.call_command('pause', until='1'), it should be considered as until arg or for (because dest of for is until as well)

We should support option names as ​documented:

** options
named options accepted on the command-line.

so

• management.call_command('pause', until='1') should work the same as calling pause --until 1
• management.call_command('pause', **{'for': '1'}) should work the same as calling pause --for 1
• management.call_command('pause', **{'for': '1', 'until': '1'}) should work the same as calling pause --for 1 --until 1 and raise an exception

[Hasan Ramezani]

Replying to Mariusz Felisiak:

I am not sure about your second example:

• management.call_command('pause', **{'for': '1'}) should work the same as calling pause --for 1

Based on the documentation, it seems we have to pass dest as keyword argument name when we define dest for arguments.

Some command options have different names when using call_command() instead of django-admin or manage.py. For example, django-admin createsuperuser --no-input translates to call_command('createsuperuser', interactive=False). To find what keyword argument name to use for call_command(), check the command’s source code for the dest argument passed to parser.add_argument().

Also, when Django ​adds required arguments in call command, it search for dest in options.

[Mariusz Felisiak]

You're right, sorry, I missed "... check the command’s source code for the dest argument passed to parser.add_argument().". In that case I would raise an error that passing dest with multiple arguments via **options is not supported.

[Hasan Ramezani]

​PR

[Mariusz Felisiak <felisiak.mariusz@…>]

In c1e4111c:

Fixed #33205 -- Made call_command() raise TypeError when dest with multiple arguments is passed.

[Mariusz Felisiak <felisiak.mariusz@…>]

In c9ebe4ca:

[4.0.x] Fixed #33205 -- Made call_command() raise TypeError when dest with multiple arguments is passed.

Backport of c1e4111c74ee9d9f48cbee5a5b7c40289203c93d from main