Fixed issue in create_user

[crazyscientist]

The function assumed that User.get_by_type_and_id returns a User instance or None. However, this called method raises a helios_auth.models.User.DoesNotExist exception.

This commit changes the behavior of create_user to match the behavior of User.get_by_type_and_id.

[crazyscientist]

Example

$ ./manage.py shell
Python 3.10.6 (main, Nov 14 2022, 16:10:14) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> import django
>>> from helios_auth.models import User
>>> from helios_auth.auth_systems.password import create_user
>>> django.VERSION
(2, 2, 24, 'final', 0)
>>> create_user("andi","very-secret-password", "Andi")
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/andi/workspace/helios-server/helios_auth/auth_systems/password.py", line 24, in create_user
    user = User.get_by_type_and_id('password', username)
  File "/home/andi/workspace/helios-server/helios_auth/models.py", line 48, in get_by_type_and_id
    return cls.objects.get(user_type = user_type, user_id = user_id)
  File "/home/andi/virtualenvs/helios/lib/python3.10/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/andi/virtualenvs/helios/lib/python3.10/site-packages/django/db/models/query.py", line 406, in get
    raise self.model.DoesNotExist(
helios_auth.models.User.DoesNotExist: User matching query does not exist.

Note: I only tested this with Python 3.10 and Django 2.2¹

Footnotes

1. I'm fairly sure, that more recent Django versions behave identically. ↩

[Copilot]

Pull request overview

This PR fixes a bug in the create_user function that incorrectly assumed User.get_by_type_and_id returns None when a user doesn't exist. The method actually raises a User.DoesNotExist exception (as confirmed by the Django ORM's objects.get() behavior), which would have caused the function to crash instead of properly handling existing users.

Key Changes:

• Replaced conditional check with try/except/else block to properly handle User.DoesNotExist exception
• Aligned error handling pattern with other usages in the same file (lines 65, 90)

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[Copilot]

The result of User.get_by_type_and_id is not assigned to any variable. While the current code works correctly for checking existence, it would be more idiomatic to assign it to a variable (e.g., user = User.get_by_type_and_id('password', username)) for consistency with other usages in the codebase (see lines 65 and 90).

Suggested change

	User.get_by_type_and_id('password', username)
	user = User.get_by_type_and_id('password', username)