title: django accessing uploaded files in model custom save, best practice?
body: <p>Ive recently been experiementing with using django</p>
  
  <p>I want to be able to run an uploaded file through imagemagick on the model save function, I realised this wasn't possible due to the file not being available till the instance had been saved</p>
  
  <p>I've got it working were the save is called at the start which then allows access to the uploaded file then re saves once its populated the other fields</p>
  
  <p>Is there a better way to achieve this? it just kinda feels wrong calling the save function twice</p>
  
  <pre><code>class uploadedFiles(models.Model):
  orignal_image = models.FileField(upload_to='userimages/')
  user = models.ForeignKey(User)
  description = models.TextField(blank=True)
  
  
  def __unicode__(self,force_insert=False, force_update=False):
      return "%s uploaded by %s" % (self.orignal_image.path, self.user) 
  
  def save(self, force_insert=False, force_update=False):
      super(uploadedFiles, self).save()
      s = ''
      cmd = subprocess.Popen(['identify', '-verbose', self.orignal_image.path], stdout=subprocess.PIPE)
      for line in cmd.stdout:
          s += line
      self.description = s
      super(uploadedFiles, self).save()
  </code></pre>