Filtering only on Annotations in Django

Question

Taking the example from: http://docs.djangoproject.com/en/dev/topics/db/aggregation/#filter-and-exclude

Publisher.objects.filter(book__rating__gt=3.0).annota         


        

Answer 1

from django.db import models

Publisher.objects.annotate(
    num_books=models.Sum(
        models.Case(
            models.When(
                book__rating__gt=3.0,
                then=1,
            ),
            default=0,
            output_field=models.IntegerField(),
        )
    )
).filter(
    num_books=0,
)