class CustomerFilter(filters.FilterSet):
    flter_region = filters.CharFilter(field_name='unit__city__province__region_region_name', lookup_expr='icontains', ,help_text='篩選的大區')
    fltr_city = filters.CharFilter(method='filter_city', lookup_expr='in')
    class Meta:
        model = TbCustomer
        fields = ['flter_region', 'fltr_city']
    def filter_city(self, queryset, name, value):
        value_list = list(filter(None, value.split(',')))
        city_list = TbUnit.objects.filter(status, city__city_name__in=value_list)
        city_id = [i.id for i in city_list]
        d = TbCustomer.objects.filter(status=0,unit_id__in=city_id).all()
        c_id = [i.id for i in d]
        return queryset.filter(id__in=c_id)