Wagtail EditHandler for fields translated with django-modeltranslations

modeltranslation_edithandler.py

from django.conf import settings
from django.db.models.fields import NOT_PROVIDED

from wagtail.admin.edit_handlers import FieldPanel, MultiFieldPanel


class TranslatedFieldPanel(MultiFieldPanel):
    """
    Allow editing of translated fields.

    This will show all translation options for the field with the given name.

    The default language will be shown first.

    If the translated field has neither blank set nor a default configured,
    the default language translation will be required.
    """
    def __init__(self, field_name='', *args, **kwargs):
        self.field_name = field_name

        languages_default_first = [
            settings.MODELTRANSLATION_DEFAULT_LANGUAGE
        ] + [
            lang for lang in settings.MODELTRANSLATION_LANGUAGES
            if lang != settings.MODELTRANSLATION_DEFAULT_LANGUAGE
        ]

        kwargs['children'] = tuple([
            FieldPanel(f"{field_name}_{lang}") for lang in languages_default_first
        ])
        super().__init__(*args, **kwargs)

    def clone_kwargs(self):
        kwargs = super().clone_kwargs()
        kwargs['field_name'] = self.field_name
        return kwargs

    def on_form_bound(self):
        super().on_form_bound()

        base_field = getattr(self.model, self.field_name).field
        if not base_field.blank or base_field.default != NOT_PROVIDED:
            self.form[
                f"{self.field_name}_{settings.MODELTRANSLATION_DEFAULT_LANGUAGE}"
            ].field.required = True