IndexError: list assignment index out of range (filling an array in a for loop with count() of objects)

I want to fill the array ‘v’ with the number of doctors in each department, I got this error :

v[i]=Doctor.objects.all().filter(idDept__deptName__contains=s.deptName).count()
~^^^

IndexError: list assignment index out of range

views.py

def accueilAdmin(request):
    if not request.user.is_staff:
        return redirect('loginAdmin')
    depts=Department.objects.all()
    v=[]
    i=1
    for s in depts:
        v[i]=Doctor.objects.all().filter(idDept__deptName__contains=s.deptName).count()
        i+=1

models.py

class Department(models.Model):
    deptName = models.CharField(max_length=50, null=False)
    ...
        return self.deptName


class Doctor(models.Model):
    name= models.CharField(max_length=50)
        ...
    idDept = models.ForeignKey(Department, on_delete=models.CASCADE, null=True)
    def __str__(self):
        return self.name

I don’t know how to solve it, I would appreciate your help, thank you.

>Solution :

Indexes start at 0, you can append to the list with:

def accueilAdmin(request):
    if not request.user.is_staff:
        return redirect('loginAdmin')
    depts = Department.objects.all()
    v = []
    for s in depts:
        v.append(
            Doctor.objects.all()
            .filter(idDept__deptName__contains=s.deptName)
            .count()
        )
        i += 1

But this is likely all not necessary and inefficent, you can just annotate your Departments with the number of Doctors:

from django.contrib.auth.decorators import user_passes_test
from django.db.models import Count
from django.urls import reverse_lazy


@user_passes_test(lambda u: u.is_staff, 'loginAdmin')
def accueil_admin(request):
    depts = Department.objects.annotate(num_doctors=Count('doctor'))
    # …

The Department objects in depts will then have an extra attribute .num_doctors with the number of related Doctors. This is done in the same query, hence it reduces the amount of queries enormously:

Note: Functions are normally written in snake_case, not PascalCase, therefore it is
advisable to rename your function to accueil_admin, not accueilAdmin.