title: Problem with model inheritance and polymorphism
body: <p>i came with new django problem. The situtaion: i have a model class UploadItemModel, i subcallss it to create uploadable items, like videos, audio files ...</p>
  
  <pre><code>class UploadItem(UserEntryModel):
      category = 'abstract item'
      file = models.FileField(upload_to=get_upload_directory) 
  </code></pre>
  
  <p>i subclass it like this:</p>
  
  <pre><code>class Video(UploadItem):
      category = 'video'
  </code></pre>
  
  <p>I need to access category attributes from a custom tag. The problem si that i am getting category='abstract item' even if the class is actually Video.</p>
  
  <p>Any clue?</p>
  
  <p>EDIT: I need to use hierarchy because i have several types of item that user can uplaod(Video, Audio files, PDF text). I need to create a class for each type, but there are lot of things in common between those classes(eg forms).</p>