通过ModelForm关系设置Django M2M的值

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 import forms
from .models import Book

class BookForm(forms.ModelForm):
    class Meta:
        model = Book
        fields = ['title', 'authors']

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

def create_book(request):
    if request.method == 'POST':
        form = BookForm(request.POST)
        if form.is_valid():
            book = form.save(commit=False)
            book.authors.clear()  # 清空authors字段的值
            authors = form.cleaned_data['authors']
            for author in authors:
                book.authors.add(author)  # 添加新的作者
            book.save()
            return redirect('book_list')
    else:
        form = BookForm()
    return render(request, 'create_book.html', {'form': form})