pretalx-musicrate/pretalx_musicrate/forms.py

from django import forms
from django_scopes.forms import SafeModelMultipleChoiceField
from i18nfield.forms import I18nModelForm

from .models import MusicrateSettings


class MusicrateSettingsForm(I18nModelForm):
    def __init__(self, *args, event=None, **kwargs):
        self.instance, _ = MusicrateSettings.objects.get_or_create(event=event)
        super().__init__(*args, **kwargs, instance=self.instance, locales=event.locales)
        if not event.submission_types.count():
            self.fields.pop("submission_types")
        else:
            self.fields["submission_types"].queryset = event.submission_types.all()

    class Meta:
        model = MusicrateSettings
        fields = ("submission_types",)
        widgets = {
            "submission_types": forms.SelectMultiple(attrs={"class": "select2"}),
        }
        field_classes = {
            "submission_types": SafeModelMultipleChoiceField,
        }