[FIXED] I want user to be able to book for the same table but not at the same time

Issue

I have a model caled BookTable and a model Table, i want users to be able to book for the same table but not at the same time but i have no clue how am i going to make it.

My BookingTable model...

class BookingTable(models.Model):
    TIME_CHOICES =[
        ('08:00', '08:00'),
        ('09:00', '09:00'),
        ('10:00', '10:00'),
        ('11:00', '11:00'),
        ('12:00', '12:00'),
        ('13:00', '13:00'),
        ('14:00', '14:00'),
        ('15:00', '15:00'),
        ('16:00', '16:00'),
        ('17:00', '17:00'),
        ('18:00', '18:00'),
        ('19:00', '19:00'),
        ('20:00', '20:00'),
        ('21:00', '21:00'),
        
    ]
     
    table = models.ForeignKey(Table, on_delete=models.CASCADE)
    user = models.OneToOneField(get_user_model(), on_delete=models.CASCADE)
    time = models.TimeField(default='00:00', choices=TIME_CHOICES)

    def get_absolute_url(self):
        return reverse("list_tables")
       
    def __str__(self) -> str:
        return self.user.username + "-" + self.table.name

My Table model...

class Table(models.Model):
    name = models.CharField(max_length=100, unique=True)
    size = models.PositiveIntegerField()
    image = models.ImageField(upload_to='static/media/images/', default='static/media/images/default.jfif')
    description = models.TextField(null=False, blank=False, default="This is a very beatiful table")
    
    def __str__(self) -> str:
        return self.name[:50]
    
    def get_absolute_url(self):
        return reverse("list_tables")

I don't know where to start from

Solution

You can add a constraint to you model; as follows:

class BookingTable(models.Model):
    ...
    
    class Meta:
        constraints = [
            models.UniqueConstraint(fields=['table', 'time'], name='unique_username_email')
        ]

For this kind of issue costraints and validators are almost always the solution. You can learn more about constraints here: https://docs.djangoproject.com/en/5.0/ref/models/constraints/

And more about validators here: https://docs.djangoproject.com/en/5.0/ref/validators/

Answered By - 42WaysToAnswerThat