Question

TEMPLATE:

 <ul id="bugs-list">
  {% for group in groups %}

      <h2>{{ group.name }}</h2> <span></span>
      {% for data in group.grab_bugs %}
          <li><a href="{{data.get_absolute_url}}">{{data.name }}</a></li>
      {% endfor %}

  {% endfor %}

  </ul>

models.py:

class BrowserGroups( models.Model ):
    name = models.CharField( max_length=100 )
    slug = models.SlugField(unique=True)
    browsers = models.ManyToManyField( 'Browser' )

    def grab_bugs(self):
        bugs = Bug.objects.filter(browser__browsergroups=self,really_bug=True).distinct()
        return bugs

    def __unicode__(self):
        return self.name

    class Meta:
        verbose_name_plural = 'Browser Groups'

I’m trying to render the number of bugs (data) near the <h2>. What would be an efficient way of including the count of data near the h2? Should I define a separate function in my model class to return the total # of bugs? Or is there a more efficient way?

Answer 1

{% with group.grab_bugs as distinct_bugs %}
    <h2>{{ group.name }}</h2> (Count: {{ distinct_bugs.count }})
    {% for data in distinct_bugs %}
        <li><a href="{{data.get_absolute_url}}">{{data.name }}</a></li>
    {% endfor %}
{% endwith %}

Explanation: the grab_bugs method of the Group class returns a querset of Bug instances. To get a count of the bugs invoke the count() method on the queryset.

This will cost you two queries (not counting the ones inside the loop). One to get the count and then next to retrieve a list of bugs.