title: Type object 'Post' has no attribute 'published' Django
body: <p>I am working on an application and I am trying to show related posts based on tags. I have everything working fine but when I load the detail view in the browser I get an error saying <code>type object 'Post' has no attribute 'published'</code> I have posted my codes below.</p>
  
  <p><strong>Model:</strong></p>
  
  <pre><code>class Post(models.Model):
      """docstring for Post."""
      STATUS_CHOICES = (
          ('drafts', 'Draft'),
          ('published', 'Published'), )
      user = models.ForeignKey(settings.AUTH_USER_MODEL, default=1) #blank=True, null=True)#default=1
      title = models.CharField(max_length = 120)
      slug = models.SlugField(unique= True)
      draft = models.BooleanField(default = False)
      publish = models.DateField(auto_now=False, auto_now_add=False)
      content = models.TextField()
      tags = TaggableManager()
      status = models.CharField(max_length=10,choices=STATUS_CHOICES, default='published')
      updated = models.DateTimeField(auto_now=True, auto_now_add=False)
      timestamp = models.DateTimeField(auto_now=False, auto_now_add=True)
  </code></pre>
  
  <p><strong>View:</strong></p>
  
  <pre><code>def view(request, slug =None):
      instance = get_object_or_404(Post, slug =slug)
      if instance.draft or instance.publish &gt; timezone.now().date():
          redirect(index)
      #content_type = ContentType.objects.get_for_model(Post)
      #obj_id = instance.id
      initial_data = {
              "content_type": instance.get_content_type,
              "object_id": instance.id
      }
      form = CommentForm(request.POST or None, initial=initial_data)
      if form.is_valid():
          #print  (form.cleaned_data)
          c_type = form.cleaned_data.get("content_type")
          content_type = ContentType.objects.get(model= c_type)
          obj_id = form.cleaned_data.get("object_id")
          c_content =form.cleaned_data.get("content")
          parent_obj = None
          try:
              parent_id = int(request.POST.get("parent_id"))
          except Exception as e:
              parent_id = None
  
          if parent_id:
              parent_query = Comment.objects.filter(parent__id= parent_id)
              if parent_query.exists():
                  parent_obj = parent_query.first()
  
          new_comment, created = Comment.objects.get_or_create(
                  user = request.user,
                  content_type = content_type,
                  object_id = obj_id,
                  content = c_content,
                  parent = parent_obj,
  
                  )
          return HttpResponseRedirect(new_comment.content_object.get_absolute_url())
  
  
      comments = instance.comments
      # List of similar posts
      post_tags_ids = instance.tags.values_list('id', flat=True)
      similar_posts = Post.published.filter(tags__in=post_tags_ids).exclude(id=instance.id)
      similar_posts = similar_posts.annotate(same_tags=Count('tags')).order_by('-same_tags','-publish')[:4]
      context = {
      #"objects": query,
      "instance": instance,
      "comments": comments,
      "form": form,
      'similar_posts': similar_posts
      }
      template = 'view.html'
      return render(request,template,context)
  </code></pre>
  
  <p>addition codes would be added on request. Thanks in advance.</p>