title: How to check ImageField is empty
body: <p>I have an ImageField in my model and when I'm saving it I want to check that if it's None or not.</p>
  
  <p>In django shell I'm calling my object's ImageField and it gives :</p>
  
  <pre><code>&gt;&gt;&gt; p.avatar
  &lt;ImageFieldFile: None&gt;
  &gt;&gt;&gt; p.avatar is None
  False
  </code></pre>
  
  <p>I found that the ImageField's name is u'', so is there any better way to do it ? </p>