title: Django. Related model returns None after primary model save
body: <p>I have two models: <code>Item</code> and <code>Photo</code>. <code>Item</code> is foreignkey to <code>Photo</code> so one item can have many photos connected which is quite usual.</p>
  
  <p>Item class:</p>
  
  <pre><code>class Item(models.Model):
  name = models.CharField('Item Name',
      max_length = 150,
      null = False,
      blank = False
  )
  description = RichTextField('Item Description')
  </code></pre>
  
  <p>Photo class:</p>
  
  <pre><code>class Photo(models.Model):
  
  path_and_rename = PathAndRename()
  
  photo = models.ImageField(upload_to = path_and_rename, blank = True, null = True)
  item = models.ForeignKey('Item', related_name = 'photo_set')
  </code></pre>
  
  <p>When I'm creating new <code>Item</code> entry with bunch of photos I'd like to do some additional stuff: launching asynchronous task for indexing and email notification of user - <code>some_async_task()</code>. I'm trying to do it by <code>Item.save()</code> method:</p>
  
  <pre><code>    def save(self):
      super(Item, self).save()
  
      some_async_task.delay(self.id)
  
  
  @task(name="something")
  def something(item_id):
      print Item.objects.get(pk=item_id).photo_set.first().photo.url
  </code></pre>
  
  <p>It seems <code>save()</code> method of Item model is exactly what I need but problem is that even after calling <code>super()</code> I can't get data about related Photo entries because such relationship doesn't exist.</p>
  
  <p>What is the best way to run method after Item entry was created and all related Photo entries were related?</p>
  
  <p><code>post_save</code> signal doesn't fix situation.</p>