Django queryset custom order

Question

I would like to make a queryset, which will first order by title then by size, but the size should be custom ordered, like the order in the list. For example

order_size_ist = ['S', 'M', 'L', 'XL', 'XXL' ]
queryset = RawMaterial.objects.order_by('title', 'size')

The size should be ordered first S, then M then L and so on. Any ideas ? Thank you in advance :)

Answer 1

You can work with a Case-When sequence to map the sizes onto integers and then sort by these integers:

from django.db.models import Case, Value, When

RawMaterial.objects.order_by(
    'title',
    Case(
        *[When(size__iexact=siz, then=Value(i))
          for i, siz in enumerate(order_size_ist)],
        default=None
    ).asc()
)