Django order_by sum of fields

Question

Is it possible to use the django ORM to order a queryset by the sum of two different fields?

For example, I have a model that looks like this:

class          


        

Answer 1

Use extra:

Component.objects.extra(select = {'total_cost' : 'material_cost + labor_cost'},
                                   order_by = ['total_cost',])[0]

Answer 2

You can use extra for this.

Component.objects.extra(
    select={'fieldsum':'material_cost + labor_cost'},
    order_by=('fieldsum',)
)

See the documentation.

Answer 3

I think it's time to provide better answer. Since django team is considering deprecating extra(), it's better to use annotate() with F() expression:

from django.db.models import F

Component.objects.annotate(fieldsum=F('material_cost') + F('labor_cost')).order_by('fieldsum')

see also https://code.djangoproject.com/ticket/25676