我正在做一个Django项目，当我尝试访问127.0.0.1:8000/articles/create时，我的Ubuntu终端出现以下错误：

/home/(my name)/django_test/article/forms.py:4: RemovedInDjango18Warning:  Creating a ModelForm without either the 'fields' attribute or the 'exclude' attribute is deprecated - form ArticleForm needs updating
class ArticleForm(forms.ModelForm):

另外，在访问我的实际本地主机站点时，我还收到以下错误消息：

ValueError at /articles/create/

The view article.views.create didn't return an HttpResponse object. It returned None instead.

这是我的forms.py文件：

from django import forms
from models import Article

class ArticleForm(forms.ModelForm):

    class Meta:
        model = Article 

这是我的views.py文件：

from django.shortcuts import render_to_response
from article.models import Article
from django.http import HttpResponse
from forms import ArticleForm
from django.http import HttpResponseRedirect
from django.core.context_processors import csrf

#import pdb; pdb.set_trace()
# Create your views here.

def articles(request):
    language = 'en-us'
    session_language = 'en-us'

    if 'lang' in request.COOKIES:
        language = request.COOKIES['lang']
    if 'lang' in request.session:
        session_language = request.session['lang']

    return render_to_response('articles.html',  
                          {'articles':
                           Article.objects.all(), 'language' : language, 
                           'session_language' : session_language})

def article(request, article_id=1):
    return render_to_response('article.html', {'article': 
                                            Article.objects.get(id=article_id) })

def language(request, language='en-us'):
    response = HttpResponse("setting language to %s" % 
                        language)

    response.set_cookie('lang', language)
    response.session['lang'] = language

    return response

def create(request):
    if request.POST:
        form = ArticleForm(request.POST)
        if form.is_valid():
            form.save()

            return HttpResponseRedirect('/articles/all')

        else:
            form = ArticleForm()

        args = {}
        args.update(csrf(request))

        args['form'] = form 

        return render_to_response('create_article.html', args)

我不确定如何解决此问题。我查看了Django文档，但找不到解决问题的方法，因此将不胜感激。