Django -如何在选择字段中显示相关的多对多字段？

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)
    authors = models.ManyToManyField(Author)

from django.contrib import admin
from .models import Book

class BookAdmin(admin.ModelAdmin):
    list_display = ('title', 'display_authors')

    def display_authors(self, obj):
        return ", ".join([author.name for author in obj.authors.all()])

admin.site.register(Book, BookAdmin)