Solution proposed in 656dca3 for issue #187 is not user-friendly nor usable in frontend

[caumons]

(I'm opening a new issue because #187 has been closed and I can't reopen it).

I've just tried the new 0.7 release and I've seen that you've included a None CheckboxField. If it's checked, then you insert a None value for that field into the database, else an empty string '' if no value was present.

I think this is a hack, instead of a real solution. Final users don't have to even know if the value has to be saved as a NULL SQL value or an empty string. This should be done automatically.

Instead of relying on this field, I'd remove it completely and apply the following simple logic:

• If the field is empty and nullable, then insert a None value
• If the field is empty and NOT nullable, then insert an empty string ''

This would be a real solution. Transparent for the user and this would finally fix the issue.

Some months ago, I did a pull request #188 which hasn't been discussed, nor merged. In that pull request I introduced a new form to allow users write the translations for the languages they wish. Forcing them to introduce at least one translation for required translatable fields. So, I can't force them to even see this None checkbox. They'd think... what the hell is this? (In fact, I thought so when I've seen it for the first time).

[zlorf]

I agree, that this 'None' checkbox can be annoying in frontend.
Here is a branch ultimate-null-formfield-solution with proposal:
https://github.com/deschler/django-modeltranslation/tree/ultimate-null-formfield-solution

Summary:
Generally formfields behave just like you described:

• If the field is empty and nullable, then insert a None value
• If the field is empty and NOT nullable, then insert an empty string ''

But it can be overridden (for example, to handle #187 - unique constraint) by new setting in TranslationOptions:

class NTTranslationOptions(TranslationOptions):
    fields = ('cnn', 'cna', 'cu', 'inn', 'ina', 'iu')
    empty_values = {'cu': None, 'ina': '', 'iu': 'both'}

None and '' are quite meaningful by their own (what will be saved to database in case of empty field). 'both' will result in what can be seen now - normal widget and None checkbox, which allow to save either empty string or None.

Moreover, one might want to use this 'both' widget, but only in admin - therefore I introduced both_empty_values_fields option in TranslationAdmin.

AND! This only apply to CharFields and it's subclasses. Other fields don't allow two empty values.

[deschler]

@zlorf: Ultimate! 👍 I feel this can be merged into master and the 0.7.x branch. Since Django 1.6 is out of the door we need to make a bugfix release because of #214 and i want to include this change.

[zlorf]

I need to write some words in docs about this, though.

[caumons]

Hi @zlorf and @deschler! It has taken a lot of time since the bug was initially reported and we finally seem to have a useful solution! It's been a really hard bug to deal with...

I've reviewed the latest commit, where @zlorf has added the docs and I think that it's perfectly explained and if the code works as described, I think that now we have a fully working solution ready for production environments.