如何在Django中对外键执行if条件

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)

authors = Author.objects.all()

for author in authors:
    books_count = Book.objects.filter(author=author).count()
    if books_count > 0:
        print(f"{author.name} 有 {books_count} 本书")
    else:
        print(f"{author.name} 无书籍")

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

authors_with_books = Author.objects.annotate(
    books_count=Case(
        When(book__isnull=False, then=1),
        default=0,
        output_field=IntegerField()
    )
)

for author in authors_with_books:
    if author.books_count > 0:
        print(f"{author.name} 有书籍")
    else:
        print(f"{author.name} 无书籍")