Breaks BooleanField with provided default value: can't save False via admin UI project-wide if using django-cassandra-engine in same project

[ilia-khaustov]

Found this issue while trying to use default kwarg with any BooleanField for any model in the project.

After setting default kwarg for model field, admin UI fails to update its value to False: changing False --> True is OK, but changing True --> False doesn't work. After some investigation found this most possible reason:

if (field_has_default and form.add_prefix(f.name) not in form.data and
            not getattr(form[f.name].field.widget,
                        'dont_use_model_field_default_for_empty_data', False)):
    continue

Condition above skips on BooleanField update when updating True --> False as field name is not present in form.data when widget value is not set (=False for CheckboxInput case). It is possible to override this behaviour by specifying widget.dont_use_model_field_default_for_empty_data = True for needed BooleanField, however, this looks like a poor workaround that should not be needed.

[srtonz]

It just took me way to long to grep for something monkeypatching django.forms.models.construct_instance. This is a critical issue as it breaks Django's admin form behavior.

@r4fek is it really necessary to change the behavior of django.forms.models.construct_instance in https://github.com/r4fek/django-cassandra-engine/blob/master/django_cassandra_engine/apps.py#L55 globally?

[r4fek]

@geotob @ilya-khaustov could you guys try with current master? I think I fixed it, but need confirmation.

[srtonz]

@r4fek thanks, this seems to have fixed it. Would you be able to release a new version with the fix please?:)

[r4fek]

@geotob Version 1.1.1 released to PyPi. Enjoy :)