如何限制Django raw_id_field的ForeignKey选择

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, limit_choices_to={'name__startswith': 'A'})

from django.contrib import admin
from .models import Book, Author

class BookAdmin(admin.ModelAdmin):
    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if db_field.name == "author":
            kwargs["queryset"] = Author.objects.filter(name__startswith='A')
        return super().formfield_for_foreignfield(db_field, request, **kwargs)

admin.site.register(Book, BookAdmin)

{% block extrahead %}
<script>
document.addEventListener('DOMContentLoaded', function() {
    var authorInput = document.querySelector('#id_author_raw_id');
    authorInput.addEventListener('change', function() {
        var selectedAuthor = authorInput.value;
        if (selectedAuthor && selectedAuthor[0] !== 'A') {
            alert('请选择名字以 "A" 开头的作者');
            authorInput.value = '';
        }
    });
});
</script>
{% endblock %}