Avoid traceback when quitting makemigrations with Ctrl-C

[Adam Johnson]

Sometimes makemigration asks you questions with its “questioner”. If you realize that you missed something due to these questions, you might want to quit with Ctrl-C and edit your models file before rerunning.

Currently, such a quit triggers Python’s default traceback:

$ ./manage.py makemigrations example
It is impossible to add a non-nullable field 'title' to book without specifying a default. This is because the database needs something to populate existing rows.
Please select a fix:
 1) Provide a one-off default now (will be set on all existing rows with a null value for this column)
 2) Quit and manually define a default value in models.py.
Select an option:  ^CTraceback (most recent call last):
  File "/.../manage.py", line 21, in <module>
    main()
    ~~~~^^
  ...
  ...
  ...
  File "/.../django/db/migrations/questioner.py", line 169, in ask_not_null_addition
    choice = self._choice_input(
        f"It is impossible to add a non-nullable field '{field_name}' "
    ...<10 lines>...
        ],
    )
  File "/Users/chainz/tmp/django-makemigrations-ctrl-c/.venv/lib/python3.13/site-packages/django/db/migrations/questioner.py", line 114, in _choice_input
    result = input()
KeyboardInterrupt

This isn’t very user-friendly: it seems like maybe you broke Django, and it pushes the question up out of the terminal window.

Instead, we could quit with minimal output, perhaps a simple message like:

Select an option:  ^C
Cancelled.

If there's a message, it should probably use ​the notice style.

[amansharma612]

I think one possible way to implement this would be to add an except KeyboardInterrupt statement after the existing except ValueError block in the _choice_input definition in questioner.py and moving the result = input() statement inside the try block. I can open a PR for the same if seems reasonable.

[amansharma612]

PR - ​https://github.com/django/django/pull/18947

[Sarah Boyce]

Thank you! Agree this makes sense, I don't think this needs documenting as might be more of a cleanup but needs tests

[Sarah Boyce <42296566+sarahboyce@…>]

In f05edb2:

Fixed #36016 -- Prevented traceback when quitting makemigrations with Ctrl-C.