Question

我尝试创建表单以将博客添加到已登录用户的订阅列表中。现在我只对form_valid的第一部分感兴趣直到＆＃39;除了＆＃39;

class AddBlogToSubList(CreateView):
model = SubscriptionList
form_class = SubsListForm
template_name = 'blog/add_blog_to_sub_list.html'
success_url = reverse_lazy('blog:blog-list')

def form_valid(self, form):
    try:
        # first I'm trying to find out if an instance of a 
        # SubscriptionList model is in the database
        model_instance = self.request.user.subscription_list

        # Then I create an instance of a form with kwarg 'instance'
        # to work with the default model instance
        f = SubsListForm(self.request.POST, instance=model_instance)

        # As far as I understand here I get a instance of a model in
        # the database with the ability to update it as I've mentioned
        # earlier instance=model_instance
        existing_instance = f.save(commit=False)

        blog = Blog.objects.get(pk=self.kwargs['blog_pk'])

        # update a subscription list of a current user with a new blog
        existing_instance.blogs_in_subscription.add(blog)

        # save an updated instance
        existing_instance.save()
        f.save_m2m()
        return super(AddBlogToSubList, self).form_valid(form)
    except SubscriptionList.DoesNotExist:
        pass

我期望的是，如果我正在更新已经在数据库中的订阅列表的实例（露水到实例= model_instance，根据django文档）＆＃39;用户＆＃39;属性将已设置。但是我得到了这个错误：

    File "D:\PyDocs\taskagain\lib\site-packages\django\db\backends\sqlite3\base.py" in execute
  328.         return Database.Cursor.execute(self, query, params)

Exception Type: IntegrityError at /blogs/3/add_to_subscription/
Exception Value: NOT NULL constraint failed: blog_subscriptionlist.user_id

表格

    from django.forms import ModelForm

from blog.models import SubscriptionList


class SubsListForm(ModelForm):
    class Meta:
        model = SubscriptionList
        fields = []

网址

urlpatterns = [
url(r'^$', BlogList.as_view(), name='blog-list'),
url(r'^(?P<blog_pk>\d+)/$', BlogDetail.as_view(), name='blog-detail'),
url(r'^(?P<blog_pk>\d+)/add_to_subscription/$', AddBlogToSubList.as_view(), name='add-to-subscription'),
url(r'^(?P<blog_pk>\d+)/subscriptions/$', SubscriptionListView.as_view(), name='subscription-list'),
url(r'^(?P<blog_pk>\d+)/create/$', PostCreate.as_view(), name='post-create'),
url(r'^(?P<blog_pk>\d+)/(?P<post_pk>\d+)/$', PostDetail.as_view(), name='post-detail'),
url(r'^(?P<blog_pk>\d+)/(?P<post_pk>\d+)/update/$', PostUpdate.as_view(), name='post-update'),
url(r'^(?P<blog_pk>\d+)/(?P<post_pk>\d+)/delete/$', PostDelete.as_view(), name='post-delete'),

模型

class SubscriptionList(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE, 
                            related_name='subscription_list')
blogs_in_subscription = models.ManyToManyField(Blog, related_name='in_subscription_lists',
                                                blank=True)

def __str__(self):
    return "%s subscription list" % self.user.username

谢谢。

使用CreateView和ModelForm时，无法从数据库中获取属性值

0 个答案: