title: filtering dropdown values in django admin
body: <pre><code>class Foo(models.Model):
      title = models.TextField()
      userid = models.IntegerField()
      image = models.CharField(max_length=100)
      def __unicode__(self):
         return self.title
  
  class Bar(models.Model):
      foo = models.ForeignKey(Foo, related_name='Foo_picks', unique=True)
      added_on = models.DateTimeField(auto_now_add=True)
  </code></pre>
  
  <p>In Django admin add_view:</p>
  
  <pre><code>def add_view(self, *args, **kwargs):
      self.exclude = ("added_on",)
      self.readonly_fields = ()
      return super(Bar, self).add_view(*args, **kwargs)
  </code></pre>
  
  <p>So, Field shows in the admin add view is <code>foo</code> Which is a drop down list and shows all the titles. Some <code>title</code> of <code>Foo</code> remains empty or ''. So, drop down list have lots of empty value because it title is empty. I want to filter out those empty values.</p>