django static annotation

Question

I want to add a static value to the results of a database query using django (so not using 'raw' SQL)

For example, if I have an object Car with fields make, model, and color, then I want my results set with extra static value to look something like this:

make     model     color    sales ----     -----     -----    ----- nissan   bluebird  black    0 ford     fiesta    red      0 toyota   camry     green    0 

I tried code like

cars= Car.objects.all().annotate(sales=0) 

but got errors. What can I do?

Cheers, Dave

--Trindaz on Fedang #django

Answer 1

Django features Value expressions:

from django.db.models import Value  cars= Car.objects.annotate(sales=Value(0)) 

Prior to Django 3.2, specify the field class:

from django.db.models import Value, IntegerField  cars= Car.objects.annotate(sales=Value(0, IntegerField()))  

Instead of IntegerField you can use all available db fields classes.