models.py

class Property(models.Model):
    price = models.DecimalField(max_digits=15, decimal_places=2)
    rooms = models.PositiveIntegerField()
    address = models.TextField(null=True, blank=True)
    city = models.CharField(max_length=255)
    country = models.CharField(max_length=255)

    class Meta:
        abstract = True


class House(Property):
     pass


class Apartment(Property):
    floor = models.PositiveIntegerField()