Django Order_BY custom function

Question

I have field in model roll_numb. Theroll_numb has values as follows.

070-001
070-007
070-343
080-002
080-008

When

Answer 1

Annotate your queryset with a custom field:

from django.db.models.functions import Substr

YourModel.objects.annotate(roll_split=Substr('roll_numb', 5)).order_by('roll_split')

If you want to always have your models ordered, just move that annotation to the model's manager:

class YourModelManager(models.Manager):
    def get_queryset(self):
        qs = super(YourModelManager, self).get_queryset()
        return qs.annotate(roll_split=Substr('roll_numb', 5)).order_by('roll_split')

class YourModel(models.Model):
    objects = YourModelManager()