Django:更改模型窗体中的字段类型,然后将其应用于模型类

我有一节课 Book :

from django.db import models
from users.models import User

class Book(models.Model):
    title = models.CharField(max_length=150)
    authors = models.ManyToManyField("Author")

哪些链接指向Author类:

class Author(models.Model):
    name = models.CharField(max_length=150)
    birthday = models.DateField()

我有一张读书班的表格叫 BookForm

from django import forms
from django.forms import CharField
from books.models import Book
class BookForm(forms.ModelForm):
    authors = CharField()
    class Meta:
        model = Book
        fields = ["title","authors"]

我想用足够简单的BookForm来创建书籍,但是我不想像默认的那样从列表中选择作者(因为它是ManyToManyField),而是希望用户能够输入文本,即每个作者的名称的逗号分隔字符串。我的观点是这样的:

def create_book(request):
    if request.user is None:
        return redirect("/users/login/")
    if request.method == "POST":
        form = BookForm(request.POST)
        if form.is_valid():
            nbook = form.save(commit=False)
            authorlist = form.authors.split(",")
            nbook.owner = request.user
            nbook.save()
            for auth in authorlist:
                nbook.authors.create(name=auth)
            return redirect("/books/")
    else:
        form = BookForm()
    return render_to_response("books/create.html", {
        "form": form,
    }, context_instance=RequestContext(request))

但这不管用。我明白错误 'BookForm' object has no attribute 'authors' . 我不确定这里是否有一个基本的问题,或者它是否只是一个语法问题,但是有人能帮个忙吗?我对Python和Django都是新手:[

谢谢!