基于类的视图 (CBV)、CreateView 和 request.user 具有多对多关系答案

【问题标题】：Class Based Views (CBV), CreateView and request.user with a many-to-many relation基于类的视图 (CBV)、CreateView 和 request.user 具有多对多关系
【发布时间】：2018-03-04 20:16:19
【问题描述】：

基于https://docs.djangoproject.com/en/1.11/topics/class-based-views/generic-editing/#models-and-request-user 中的示例 - 但使用多对多关系而不是外键关系：

models.py

from django.contrib.auth.models import User
from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=200)
    owners = models.ManyToManyField(User, related_name='owners_')

views.py

from django.views.generic.edit import CreateView
from myapp.models import Author

class AuthorCreate(CreateView):
    model = Author
    fields = ['name']

    def form_valid(self, form):
        form.instance.owners = self.request.user
        return super(AuthorCreate, self).form_valid(form)

会输出

"<Author: test>" needs to have a value for field "id" before this many-to-many relationship can be used.

如何避免这种情况？

【问题讨论】：

标签： django django-forms django-views django-class-based-views

【解决方案1】：

像这样编辑你的视图，

class AuthorCreate(CreateView):
    model = Author
    fields = ['name']

    def form_valid(self, form):
        self.object = form.save()
        self.object.owners.add(self.request.user)
        self.object.save()
        return HttpResponseRedirect(self.get_success_url())

CreateView 继承自 ModelFormMixin 和 FormMixin。调用super() 只会导致保存模型并重定向到success_url。对于ManyToManyField，在创建ManyToMany 关系之前，对象需要有primary_key（即对象需要保存在数据库中），因此，通过显式调用以下方法来覆盖form_valid() 方法两个父类都可以解决您的问题。

【讨论】：