Hotel/hotel/rooms/models.py

from django.db import models
from django.core.validators import MinValueValidator


class RoomType(models.Model):
    room_type = models.CharField(max_length=40)

    def __str__(self):
        return self.room_type


class Room(models.Model):
    room_number = models.IntegerField(
        primary_key=True,
        validators=[
            MinValueValidator(1)
        ]
    )

    price = models.IntegerField(
        validators=[
            MinValueValidator(1)
        ]
    )

    room_type = models.ForeignKey(RoomType, on_delete=models.CASCADE)
    reserved = models.BooleanField()

    def __str__(self):
        return str(self.room_number)


class Client(models.Model):
    id_number = models.CharField(max_length=9, primary_key=True)
    name = models.CharField(max_length=40)
    surname = models.CharField(max_length=40)

    def __str__(self):
        return self.name, self.surname


class Reservation(models.Model):
    room_number = models.ForeignKey(Room, on_delete=models.CASCADE)
    client_id = models.ForeignKey(Client, on_delete=models.CASCADE)
    begin_date = models.DateField()
    end_date = models.DateField()