ntegrityError NOT NULL约束失败请求方法：POST

Question

我的观点中有这个功能。在django 1.9上工作的

def post_create(request):
    form = PostForm(request.POST or None)
    if form.is_valid():
        instance = form.save(commit=False)
        print(form.cleaned_data.get("title"))
        instance.save()
    context = {
        "form": form,
    }
    return render(request, "post_form.html", context)

url.py

urlpatterns = [
    url(r'^$', views.post_list),
    url(r'^create/$', views.post_create),
    url(r'^(?P<id>\d+)/$', views.post_detail, name='detail'),
    url(r'^update/$', views.post_update),
    url(r'^delete/$', views.post_delete)
]

models.py

from django.db import models
from django.core.urlresolvers import reverse


class Post(models.Model):
    title = models.CharField(max_length=120)
    content = models.TextField()
    updated = models.DateTimeField(auto_now=False, auto_now_add=False)
    timestamp = models.DateTimeField(auto_now=False, auto_now_add=False)

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse("posts:detail", kwargs={"id": self.id})

但这是我在django 1.10上写的时候得到的：

   / posts / create /中的IntegrityError   NOT NULL约束失败：posts_post.updated   请求方法：POST

任何想法？