Python list: list index out of range

Question

I am not so much familiar with python and got this code from a friend of mine and need some community help here to solve this issue.I'm getting "list index out of range" error from the following line.

days = list(zip(Leave_type.objects.filter(type=leavetype).values_list('max_days', flat=True))[0])

Note: I have already execute migrations and setup my database already.

def timeoffapply(request):

if not request.session.get('id', None):
    return render(request, 'login.html')
else:
    stdate = request.POST['startDate']
    enddate = request.POST['endDate']
    leavetype = request.POST['leaveType']
    days = list(zip(Leave_type.objects.filter(type=leavetype).values_list('max_days', flat=True))[0])
    d1 = datetime.strptime(stdate, "%Y-%m-%d")
    d2 = datetime.strptime(enddate, "%Y-%m-%d")
    d3 = abs((d2 - d1).days)+1
    empid = (request.session['id'])[0]
    countdays = Leave.objects.filter(Emp_id = empid,type=leavetype).aggregate(Sum('days'))
    if countdays['days__sum'] == None:
        finaday = (days[0] - 0)
    else:
        finaday=(days[0] - countdays['days__sum'])
    if enddate>=stdate:
        if finaday >= d3:
            getleaveid = list(zip(Leave_type.objects.filter(type=leavetype).values_list('id', flat=True))[0])
            split_lt_id = ("".join(str(e) for e in getleaveid))
            empid = (request.session['id'])[0]
            get_emp_name = list(zip(Employee.objects.filter(id=empid).values_list('name', flat=True))[0])
            get_emp_name = ("".join(str(e) for e in get_emp_name))
            empid = (request.session['id'])[0]
            leave_id = Leave.objects.all().count()
            test = Leave(id=(leave_id + 1), name=get_emp_name, type=leavetype, start_date=stdate, end_date=enddate,
                         days=d3,
                         status="pending")

            test.Emp_id_id = empid
            test.leave_type_id_id = split_lt_id
            test.save()
            return HttpResponseRedirect('/')
        else:
            qs = Leave.objects.all().filter(Emp_id=(request.session['id'])[0])
            context = {
                "qs": qs,
                "error": "true",
                "msg": "You are allowed to have holidays for " + str(finaday) + " days in " +str(leavetype)
            }
            return render(request, 'timeoff.html', context)

print the components in the right part of your assignment, before the assignment, and you should find the error cause. — progmatico
– progmatico, Commented Mar 7, 2018 at 14:49
Do you want to become more familiar with Python? This code could be improved in many ways (finaday = (days[0] - 0)...), which would make your job of understanding errors easier. That line causing the error is also quite odd (the zip is unnecessary, a slice would do, but even that is unnecessary, because the only use of days is days[0], so you could just get the first result). Anyway, the error message doesn't lie; the list must be empty, and you can follow progmatico's advice and do some prints to find out why that's different from your expectation. — Paulo Almeida
– Paulo Almeida, Commented Mar 7, 2018 at 16:39

Ritesh Agrawal · Accepted Answer · 2018-03-07 14:49:32Z

3

There can be a case that list returned from Leave_type.objects.filter(type=leavetype).values_list('max_days', flat=True) is empty and you are accessing first element in the empty list using [0]. So causing list index out of range error.

answered Mar 7, 2018 at 14:49

Ritesh Agrawal

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2 Comments

C0deSlayer Over a year ago

I populated my database table regarding to leave type and tried debugging my program again but i'm still getting the same error

AnonymousUser Over a year ago

I solved this with a Python Try: and Except: statement.

r_zelazny · Accepted Answer · 2018-03-07 14:50:24Z

1

The problem is simply that the queryset returned from the Leave_type model is empty; therefore you cannot access it.

answered Mar 7, 2018 at 14:50

r_zelazny

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2 Comments

C0deSlayer Over a year ago

I populated my database table regarding to leave type and tried debugging my program again but i'm still getting the same error

r_zelazny Over a year ago

If you add check = Leave_type.objects.filter(type=leavetype) to your code above the line in question is check an empty queryset? Or does if have data? You may have data in the database but your query is not returning it.

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