title: form object has no attribute 'has_header'
body: <p>I'm new to django. I have news app with view, which renders a page for each news:</p>
  
  <pre><code>def news_page(request, news_id):
      news = News.objects.get(pk=news_id)
      tags = news.tags.all()
      category = news.category
      comments = news.comment_set.all()
      form = add_comment(request, news.id)
      return render(request, 'news/news_page.html', {'form': form, 'news': news, 'tags': tags, 'category': category, 'user': request.user, 'comments': comments})
  </code></pre>
  
  <p>And I've created comment app:
  models.py:</p>
  
  <pre><code>class Comment(models.Model):
      author = models.ForeignKey(User)
      comment_body = models.CharField(max_length=500)
      news = models.ForeignKey(News)
          pub_date = models.DateTineField(default = datetime.datetime.now())
  </code></pre>
  
  <p>forms.py:</p>
  
  <pre><code>class AddCommentForm(ModelForm):
      comment_body = forms.CharField(widget=forms.Textarea)
  
      class Meta():
          model = Comment
          exclude = ('author', 'news','pub_date',)
  </code></pre>
  
  <p>I'l try realize comments.view function add_comment which news_page view (above) use:</p>
  
  <pre><code>def add_comment(request, news_id):
      news = News.objects.get(pk=news_id)
      if request.method == 'POST':
          form = AddCommentForm(request.POST)
          if form.is_valid:
              comment = form.save(commit=False)
              comment.author = request.user
              comment.news = news
              comment.save()
      else:
          form = AddCommentForm()
      return form
  </code></pre>
  
  <p>But I've got error 'AddCommentForm' object has no attribute 'has_header' . I think that's happen because add_comment view don't have HttpResponse. How should I rewrite code so that the idea become ​​working.
   Error traceback</p>
  
  <pre><code>Internal Server Error: /news/15/comment/
  Traceback (most recent call last):
    File "C:\Python27\myproject\djcode\first_venv\venv\lib\site-packages\django\core\handlers\base.py"
  , line 187, in get_response
      response = middleware_method(request, response)
    File "C:\Python27\myproject\djcode\first_venv\venv\lib\site-packages\django\contrib\sessions\middl
  eware.py", line 26, in process_response
      patch_vary_headers(response, ('Cookie',))
    File "C:\Python27\myproject\djcode\first_venv\venv\lib\site-packages\django\utils\cache.py", line
  142, in patch_vary_headers
      if response.has_header('Vary'):
  AttributeError: 'AddCommentForm' object has no attribute 'has_header'
  </code></pre>
  
  <p>Thank's!</p>