Prefilled admin inlines (v2)

from django import forms
from django.conf import settings
from django.contrib import admin
from django.contrib.admin.utils import flatten_fieldsets
from django.forms.models import BaseInlineFormSet


class ShopLocationFormset(BaseInlineFormSet):
    """
    Prefilled formset
    """

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        data = {item.building_id: item.building for item in self.queryset}
        self.initial = [
            {'building': building, 'base_shop': self.instance}
            for building in (
                list(data.values())
                + list(Building.objects.exclude(id__in=data.keys()))
            )
        ]


class ShopLocationForm(forms.ModelForm):

    class Meta:
        fields = '__all__'
        model = ShopLocation

    def __init__(self, *args, **kwargs):
        shop = kwargs.get('initial', {}).pop('base_shop', None)
        super().__init__(*args, **kwargs)
        pavilion_qs = self.fields['pavilion'].queryset
        if shop:
            pavilion_qs = pavilion_qs.filter(shop=shop)

        building = self.initial.get('building')
        if building:
            pavilion_qs = pavilion_qs.filter(floor__building=building)

        self.fields['pavilion'].queryset = pavilion_qs
        if not pavilion_qs:
            self.fields['pavilion'].required = False
            for field in trans_field('location'):
                self.fields[field].required = False


class ShopLocationInline(TranslationTabularInline):
    can_delete = False
    form = ShopLocationForm
    formset = ShopLocationFormset
    model = ShopLocation

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.inline_count = Building.objects.count()

    def get_min_num(self, request, obj=None, **kwargs):
        return self.inline_count

    def get_max_num(self, request, obj=None, **kwargs):
        return self.inline_count

    def get_extra(self, request, obj=None, **kwargs):
        return self.inline_count

    def formfield_for_dbfield(self, db_field, request, **kwargs):
        field = super().formfield_for_dbfield(db_field, request, **kwargs)
        if db_field.name == 'building':
            field.widget.attrs['class'] = 'is-disabled'
        return field


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