Django

跟着《 python 编程从入门到实践》练习 Django，遇到如下问题：创建了一个 Topic 表单，有一个 Entry 表单用外键链接到 Topic，在试图函数里定义了修改 Entry 的函数如下： def edit_entry(request, entry_id):

"""修改条目"""

entry = Entry.objects.get(id=entry_id)
topic = entry.topic

if request.method != 'POST':
    form = EntryForm(instance=entry)
else:
    form = EntryForm(instance=entry, data=request.POST.get('fields'))
    if form.is_valid():
       	form.save()
        return HttpResponseRedirect(reverse('xs:topic', args=[topic.id]))

context = {'topic': topic, 'form': form, 'entry': entry}
return render(request, 'xs/edit_entry.html', context)

现在我想修改 Topic，跟着上面的函数定义了下面这个函数：

def edit_topic(request, topic_id):

"""修改主题"""

topic = Topic.objects.get(id=topic_id)

if request.method != 'POST':
    form = TopicForm(instance=topic)
else:
    form = TopicForm(instance=topic, data=request.POST.get('fields'))
    if form.is_valid():
        form.save()
        return HttpResponseRedirect(reverse('xs:topics'))

context = {'topic': topic, 'form': form}
return render(request, 'xs/edit_topic.html', context)

这就出问题了，第二个 if 语句(if form.is_valid())似乎没有执行，导致没有跳转至 topics.html 页面