`ValueError: min() arg is an empty sequence` as result while using `management.call_command()`

Using Django Mystery Errors
1

Hello,

for a project I am using Django management commands to create a CLI. Until now the project is really basic, nothing fancy.

My starting point is python manage.py start:

# start.py

from django.core.management.base import BaseCommand
from django.core.management import call_command

from cli.menu import get_start_menu

class Command(BaseCommand):
    help = "Start of the program."

    def handle(self, *args, **options):
        choice = get_start_menu("Welcome to Epic Events")

        if choice == 1:
            call_command("account_manager")
        if choice == 2:
            call_command("contract")
        if choice == 3:
            call_command("event")

get_start_menu is just creating a nice menu for the terminal.

This menu is working fine, the call_command() methods are working as expected.

My choice will be 1, so I call account_manager.py:

# account_manager.py

from django.contrib.auth import get_user_model
from django.core.management import call_command
from django.core.management.base import BaseCommand

from cli.menu import get_app_menu

UserModel = get_user_model()


class Command(BaseCommand):
    help = "Menu for all operations around the account managers."

    def handle(self, *args, **options):
        choice = get_app_menu("account manager")

        all_users = UserModel.objects.all()

        if choice == 4:
            call_command("start")
        if choice == 1:
            call_command(
                "account_manager_create",
                user=all_users[1],
                first_name="John",
                last_name="Doe",
                role="Management",
            )

When my second choice will be 1 again, I want to call the command 'account_manager_create", I get this output:

Traceback (most recent call last):
  File "/home/Desktop/P12/manage.py", line 22, in <module>
    main()
  File "/home/Desktop/P12/manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 442, in execute_from_command_line
    utility.execute()
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 412, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 458, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/Desktop/P12/cli/management/commands/start.py", line 14, in handle
    call_command("account_manager")
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 194, in call_command
    return command.execute(*args, **defaults)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/base.py", line 458, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/Desktop/P12/accounts/management/commands/account_manager.py", line 21, in handle
    call_command(
  File "/home/Desktop/P12/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 164, in call_command
    parse_args.append(min(opt.option_strings))
                      ^^^^^^^^^^^^^^^^^^^^^^^
ValueError: min() arg is an empty sequence

What have I tried:

  • I have deleted one argument, two arguments three arguments inside the call_command( "account_manager_create", user=all_users[1], first_name="John", last_name="Doe", role="Management", )
    the result is the same output of the traceback as above.

  • If I delete all the arguments inside the call_command( "account_manager_create", user=all_users[1], first_name="John", last_name="Doe", role="Management", )
    the result is this traceback (what makes totally sense):

CommandError: Error: the following arguments are required: user, first_name, last_name, role

I do not understand and can not find out why I get the output: ValueError: min() arg is an empty sequence when calling the command ‘account_manager_create’.

I am using: Django==5.0

This is the ‘account_manager_create.py’ file:

# account_manager_create.py

from django.core.management.base import BaseCommand

from accounts.models import AccountManager


class Command(BaseCommand):
    help = "Creates a new account manager."

    def add_arguments(self, parser):
        parser.add_argument("user", type=int, help="Enter the user id.")
        parser.add_argument("first_name", type=str, help="Enter the first name.")
        parser.add_argument("last_name", type=str, help="Enter the last name.")
        parser.add_argument("role", type=str, help="Enter the role.")

    def handle(self, *args, **options):

        account_manager = AccountManager(
            user=options["user"],
            first_name=options["first_name"],
            last_name=options["last_name"],
            role=options["role"],
        )
        account_manager.save()

        self.stdout.write("New account manager was created.")

I have gotten the hint: “it seems like the issue might be related to how Django’s call_command() function handles arguments”
Is that possible or can you point to my mistake in my code? I would like to know what the problem is and where I can check to resolve this issue.

Cheers,
Doro

2

I’m guessing that the issue here is that you’re trying to pass a complete object as a command line parameter, and that’s not going to work. (all_users[1] would be passing the second entry in the all_users result set)
I think what you’d be looking to pass here would be all_users[1].id

3

No, unfortunately that tiny but important change is not changing the error. I receive the same traceback.

4

Found the mistake. The arguments where passed in the wrong way. The correct way is:

# account_manager.py

class Command(BaseCommand):
    help = "Menu for all operations around the account managers."

    def handle(self, *args, **options):
        choice = get_app_menu("account manager")

        all_users = UserModel.objects.all()

        if choice == 4:
            call_command("start")
        if choice == 1:
            call_command(
                "account_manager_create",
                all_users[1].id,
                "John",
                "Doe",
                "Management",
            )

No need to specify the arguments, just pass the arguments.

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