django SimpleListFilter
<p>Let's say I have a model like this:</p>

<pre><code># models.py

class Customer(models.Model):
    customer_name=models.CharField(max_length=50)
    licence_key=models.CharField(max_length=100)
    exp_date=models.DateTimeField(blank=True, null=True)

    def __unicode__(self):
        return self.customer_name
</code></pre>

<p>I want to have a custom list filter in admin site that shows customer that their <code>exp_date</code> has been passed. It should have two parameters <code>valid</code> and <code>invalid</code>  for example and compare <code>exp_date</code> with today's date and show the result. I've read it can be done by simplelistfilter but I couldn't figure how.</p>

<p>Thank you and sorry for my english</p>