title: AssertionError in django
body: <p>I've been pulling my hair out on this one and it seems like there is a really simple solution for it but I'm too blind to see it.
  I've upgraded from Django 1.4.3 to Django 1.6 and ever since then I get an assertion error while trying to get DateTimeField to work.</p>
  
  <p>Here's my model</p>
  
  <pre><code>class Article(models.Model):
  '''Article Model'''
  
  banner = models.ImageField(verbose_name="Banner", null=True, blank=True, upload_to='ajax_uploads/banners', max_length=300)
  
  title = models.CharField(
      verbose_name = _(u'Title'),
      help_text = _(u' '),
      max_length = 255
  )
  slug = models.SlugField(
      verbose_name = _(u'Slug'),
      help_text = _(u'Uri identifier.'),
      max_length = 255
  )
  content_markdown = models.TextField(
      verbose_name = _(u'Content (Markup)'),
      help_text = _(u' '),
  )
  content_markup = models.TextField(
      verbose_name = _(u'Content (Markup)'),
      help_text = _(u' '),
  )
  categories = models.ManyToManyField(
      Category,
      verbose_name = _(u'Categories'),
      help_text = _(u' '),
      null = True,
      blank = True
  )
  date_publish = models.DateTimeField(
      default=datetime.date.today,
      verbose_name = _(u'Publish Date'),
      help_text = _(u' ')
  )
  
  class Meta:
      app_label = _(u'blog')
      verbose_name = _(u'Article')
      verbose_name_plural = (u'Articles')
      ordering = ['-date_publish']
  
  def save(self):
      self.content_markup = markdown(self.content_markdown, ['codehilite'])
      super(Article, self).save()
  
  def __unicode__(self):
          return '%s' % (self.title,)
  </code></pre>
  
  <p>views.py:</p>
  
  <pre><code>def index(request):
  '''News index'''
  archive_dates = Article.objects.dates('date_publish','month', order='DESC')
  categories = Category.objects.all()
  
  page = request.GET.get('page')
  article_queryset = Article.objects.all()
  paginator = Paginator(article_queryset, 5)
  
  try:
      articles = paginator.page(page)
  except PageNotAnInteger:
      #If page requested is not an integer, deliver first page.
      articles = paginator.page(1)
  except EmptyPage:
      #If page requested is out of range, deliver last page of results.
      articles = paginator.page(paginator.num_pages)
  
  return render(
      request,
      'blog/article/index.html',
  {
      'articles' : articles,
      'archive_dates' : archive_dates,
      'categories' : categories
  }
  )
  </code></pre>
  
  <p>and template</p>
  
  <pre><code>                        &lt;div class="8u skel-cell-important"&gt;
                                      {% for item in articles %}
                                              &lt;!-- Content --&gt;
                                                  &lt;article class="box is-post"&gt;
                                                      &lt;a href="{% url "blog-article-single" slug=item.slug %}" class="image image-full"&gt;&lt;img src="/media/{{ item.banner }}" alt="" /&gt;&lt;/a&gt;
                                                      &lt;header&gt;
                                                          &lt;h2&gt;&lt;a href="{% url "blog-article-single" slug=item.slug %}"&gt;{{ item.title }}&lt;/a&gt;&lt;/h2&gt;
                                                          &lt;span class="byline"&gt;Published {{  item.date_publish|date:"j, M, Y" }}&lt;/span&gt;
                                                      &lt;/header&gt;
                                                      &lt;p&gt;
                                                          {{ item.content_markup|safe|slice:":250" }}...
                                                      &lt;/p&gt;
                                                  &lt;/article&gt;
                                      {% endfor %}
                                          &lt;/div&gt;
  </code></pre>
  
  <p>and finally error traceback:</p>
  
  <pre><code>AssertionError at /blog/
  
  'date_publish' is a DateTimeField, not a DateField.
  
  Request Method:     GET
  Request URL:    http://localhost:8000/blog/
  Django Version:     1.6.1
  Exception Type:     AssertionError
  Exception Value:    
  
  'date_publish' is a DateTimeField, not a DateField.
  
  Exception Location:     /usr/local/lib/python2.7/dist-packages/django/db/models/sql/subqueries.py in _check_field, line 258
  Python Executable:  /usr/bin/python2.7
  Python Version:     2.7.3
  Python Path:    
  
  ['/home/user/paperpxl',
   '/usr/lib/python2.7',
   '/usr/lib/python2.7/plat-linux2',
   '/usr/lib/python2.7/lib-tk',
   '/usr/lib/python2.7/lib-old',
   '/usr/lib/python2.7/lib-dynload',
   '/usr/local/lib/python2.7/dist-packages',
   '/usr/lib/python2.7/dist-packages',
   '/usr/lib/python2.7/dist-packages/PIL',
   '/usr/lib/python2.7/dist-packages/gst-0.10',
   '/usr/lib/python2.7/dist-packages/gtk-2.0',
   '/usr/lib/pymodules/python2.7',
   '/usr/lib/python2.7/dist-packages/ubuntu-sso-client',
   '/usr/lib/python2.7/dist-packages/ubuntuone-client',
   '/usr/lib/python2.7/dist-packages/ubuntuone-control-panel',
   '/usr/lib/python2.7/dist-packages/ubuntuone-couch',
   '/usr/lib/python2.7/dist-packages/ubuntuone-installer',
   '/usr/lib/python2.7/dist-packages/ubuntuone-storage-protocol']
  
  Server time:    Thu, 19 Dec 2013 15:28:43 +0000
  </code></pre>
  
  <p>Any kind of help would be appreciated!</p>
  
  <p><strong>EDIT</strong> : Thanks for your help guys, I'm going back to the release notes to read through them again! I wish I had an eye for detail like you do.</p>