title: AttributeError: 'ManyRelatedManager' object has no attribute 'add'? I do like in django website but got this error
body: <pre><code>for item in data:
      category_id = item['category_id']
      del item['category_id']
  
      category = Category.objects.get(pk=category_id)
  
      code = item['code']
  
      try:
          article = Article.objects.get(pk=code)
      except:
          article = Article(**item)
          article.save()
  
      # at this point I have the article &amp; category, but the next
      # statement throws me an error:
      category.articles.add(article)
      category.save()
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>   AttributeError: 'ManyRelatedManager' object has no attribute 'add'
  </code></pre>