在Django中，如何将一个模型对象添加到另一个具有多对一关系的模型的ModelForm模板？

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)
    # 其他字段...

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

from django import forms
from .models import Book

class BookForm(forms.ModelForm):
    class Meta:
        model = Book
        fields = ['title', 'author']
        widgets = {
            'author': forms.Select(attrs={'class': 'form-control'}),
        }

from django.shortcuts import render, redirect
from .forms import BookForm

def add_book(request):
    if request.method == 'POST':
        form = BookForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('book_list')
    else:
        form = BookForm()
    return render(request, 'add_book.html', {'form': form})

<form method="post">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit">添加书籍</button>
</form>