title: Define and insert age in django template
body: <p>I have a model, view and template:</p>
  <p><strong>model</strong></p>
  <pre><code>class Peoples(models.Model):
      l_name = models.CharField(max_length=50)
      f_name = models.CharField(max_length=50)
      m_name = models.CharField(max_length=50)
      tab_number = models.CharField(max_length=5)
      birthday = models.DateField(null=True, blank=True)
      post = models.CharField(max_length=250, blank=True)
      workplace = models.ForeignKey(Workplace, null=True, blank=True)
      skill = models.CharField(max_length=20, blank=True)
      dopuska = models.TextField(blank=True)
      srok_dopuskov = models.DateField(null=True, blank=True)
      photo = models.ImageField(upload_to='img',blank=True)
      class Meta:
          ordering = ('l_name',)
      def __unicode__(self):
          return self.l_name
      def age(self):
          import datetime
          return int((datetime.datetime.now() - self.birthday).days / 365.25  )
      age = property(age)
  </code></pre>
  <p><strong>view</strong></p>
  <pre><code>def view_persone(request, tab_number):
      return direct_to_template(request, 'person.html', {
         'persone': Peoples.objects.filter(tab_number=tab_number),
      })
  </code></pre>
  <p><strong>template</strong></p>
  <pre><code>{% for person in persone %}
      Возраст: &lt;b&gt;{{ person.age }}&lt;/b&gt;
  {% endfor %}
  </code></pre>
  <p>But the field in template where should be an age is empty. why?</p>