title: Django - FileField check if None
body: <p>I have a model with an optional file field</p>
  
  <pre><code>class MyModel(models.Model):
    name = models.CharField(max_length=50)
    sound = models.FileField(upload_to='audio/', blank=True)
  </code></pre>
  
  <hr>
  
  <p>Let's put a value</p>
  
  <pre><code>&gt;&gt;&gt; test = MyModel(name='machin')
  &gt;&gt;&gt; test.save()
  </code></pre>
  
  <hr>
  
  <p>Why do I get that ?</p>
  
  <pre><code>&gt;&gt;&gt; test.sound
  &lt;FieldFile: None&gt;
  &gt;&gt;&gt; test.sound is None
  False
  </code></pre>
  
  <hr>
  
  <p>How can I check if there is a file set ?  </p>