How to automatically populate a ForeignKey field in Django?

Question

Django

Hello. There are two models :

class Hotels(models.Model):
    vip = models.BooleanField(default = False, verbose_name = 'VIP размещение')
    title = models.CharField(max_length=200, verbose_name="Название")
    slug = models.SlugField(unique=True, verbose_name="URL")
    category = models.ForeignKey(Category, verbose_name='Раздел обьявления')
    place = models.ForeignKey(Place, verbose_name='Место расположения')

class Numbers(models.Model):
    title = models.ForeignKey(NumberTitle, verbose_name='Название')
    hotel = models.ForeignKey(Hotels, blank = True, null=True, verbose_name='Отель или гостевой дом, если есть')
    place = models.ForeignKey(Place, default="", verbose_name='Место расположения')

First, the user adds a hotel, then a number to this hotel. It is necessary that the place field in the form for adding a number is automatically filled with the place value from hotel. How to implement it?

Answer 1

Why implement it in a form? It's better to do it in pre_save Numbers.

@receiver(pre_save, sender=Numbers)
def fill_place(sender, instance, **kwargs):
    instance.place = instance.hotel.place

Answer 2

After creating the hotel, we send the user to the hotel page and by the URL it will be clear to you which hotel the room is being added to

Answer 3

The question really needs to be asked here is why duplicate the place field in the Number model if it uniquely matches the field from hotel?