title: Filtering Many-to-Many relationship by Relationship field in Django
body: <p>I'm trying to filter many-to-many relationship by some <strong>through Class</strong> field. </p>
  
  <p>Quoting the Django documentation, i will explain my goal</p>
  
  <pre><code>class Person(models.Model):
        name = models.CharField(max_length=128)
  
        def __unicode__(self):
            return self.name
  
  class Group(models.Model):
        name = models.CharField(max_length=128)
        members = models.ManyToManyField(Person, through='Membership')
  
        def __unicode__(self):
            return self.name
  
  class Membership(models.Model):
        person = models.ForeignKey(Person)
        group = models.ForeignKey(Group)
        date_joined = models.DateField()
        invite_reason = models.CharField(max_length=64)
  </code></pre>
  
  <p>In this example my goal sould be filter many to many relationship and obtain only the <strong>Person</strong> who has joined some <strong>Group</strong> starting from certain date (<strong>date_joined field</strong>).</p>
  
  <p>Is it possible? </p>