`Contest.is_private` and `Problem.is_organization_private` can desync

[kiritofeng]

Currently Contest.is_private, Contest.is_organization_private, Contest.limit_join_organizations, and Problem.is_organization_private are computed on save_model. However, if all associated Organization or Profile objects is deleted, these booleans will desync.

The booleans will be recomputed on model save, and the probability of this bug occurring naturally are quite low. We could fix this by writing listeners, or we could wait for the site to update to Django 5 and use https://docs.djangoproject.com/en/5.1/ref/models/fields/#generatedfield.

[Ninjaclasher]

Generated fields might not work here:

The expressions should be deterministic and only reference fields within the model (in the same database table). Generated fields cannot reference other generated fields. Database backends can impose further restrictions.

Many to many fields are stored in a different table.

[kiritofeng]

I suppose we'll have to implement a listener then ...