Django error: list index out of range (when there's no objects)

Question

Everything works fine until I delete all the objects and try to trigger the url, then it gives me this traceback: list index out of range. I can't use get because there might be more than one object and using [0] with filter leads me to this error when there's no object present, any way around this? I'm trying to get the recently created object of the Ticket model (if created that is) and then perform the logic, so that if the customer doesn't have any tickets, nothing happens but if the customer does then the logic happens

Models

class Ticket(models.Model):
    date_posted = models.DateField(auto_now_add=True, blank=True, null=True)
    customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, blank=True, null=True)

Views

try:
    ticket = Ticket.objects.filter(customer=customer).order_by("-id")[0]
    now = datetime.now().date()
    set_date = ticket.date_posted
    check_time = now - set_date <= timedelta(hours=24)
    if check_time:
        print('working')
    else:
        print('not working')
except Ticket.DoesNotExist:
    ticket = None

context = {"check_time": check_time}

Osman · Accepted Answer · 2022-12-02 14:20:11Z

2

You can also do this:

ticket = Ticket.objects.filter(customer=customer).order_by("-id").first() or None
if ticket is not None:    
    now = datetime.now().date()
    set_date = ticket.date_posted
    check_time = now - set_date <= timedelta(hours=24)
    if check_time:
        print('working')
    else:
        print('not working')
    context = {"check_time": check_time}

instead of:

ticket = Ticket.objects.filter(customer=customer).order_by("-id")[0]

edited Dec 2, 2022 at 14:20

answered Nov 30, 2022 at 9:26

Osman

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2 Comments

betty_ Over a year ago

but doing this would give me none type no attribute date_posted error, how would I fix that?

Osman Over a year ago

You need to check the value returned. if ticket is not None: do something...

ruddra · Accepted Answer · 2022-11-30 13:32:52Z

1

Instead of this:

ticket = Ticket.objects.filter(customer=customer).order_by("-id")[0]

Use this using exists() which is a very efficient way if there is any object exist in DB:

tickets = Ticket.objects.filter(customer=customer).order_by("-id")
if tickets.exists():
   ticket = tickets.first()
else:
   ticket = None

Update

You can do the query inside the filter function.

tickets = Ticket.objects.filter(customer=customer, date_posted__lte=timezone.now().date() - timedelta(hours=24))

context = {"check_time": tickets.exists()}

edited Nov 30, 2022 at 13:32

answered Nov 30, 2022 at 8:27

ruddra

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3 Comments

betty_ Over a year ago

now that check_time is gonna be inside of the if statement, how would I call it in context?

ruddra Over a year ago

I have updated the answer. You can do this checking within the filter function

betty_ Over a year ago

yh but I would still require the context tho, cuz I need to pass it to the template

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