Django - Divide query into subgroups by attribute

Question

I have a model that looks like this:

class ListEntry(models.Model):
    STATUS_CHOICES = (
        ('PL', _('Playing')),
        ('CO', _('Completed')),
        ('OH', _('On-hold')),
        ('DR', _('Dropped')),
        ('WA', _('Want to play')),
    )
    user = models.ForeignKey(User)
    game = models.ForeignKey(Game)
    status = models.CharField(_('Status'), max_length=2,
                              choices=STATUS_CHOICES)

In my views I'm filtering the entries by user like this:

class GameListByUserView(ListView):
    model = ListEntry
    template_name = 'game_list_by_user.html'

    def get_queryset(self):
        self.user_profile = get_object_or_404(User, username=self.kwargs['slug'])
        return ListEntry.objects.filter(user=self.user_profile)

    def get_context_data(self, **kwargs):
        context = super(GameListByUserView, self).get_context_data(**kwargs)
        context['user_profile'] = self.user_profile
        return context

What I'm trying to do now is split this query (ListEntry.objects.filter(user=self.user_profile)) into subgroups depending on the status attribute, so the rendered template looks like:

UserFoo's list
=========================

Playing

Game 1
Game 2
Game 3


Completed

Game 4
Game 5
Game 6

I know I can do something like:

q = ListEntry.objects.filter(user=self.user_profile)
games_dict = {}
games_dict['playing'] = q.filter(status='PL')
games_dict['completed'] = q.filter(status='CO')

And so on, and iterate over the keys in the template. Or (in the template):

{% for s in status_choices %}
  {% for entry in object_list %}
    {% if entry.status == s %}
      Render things
    {% endif %}
  {% endfor %}
{% endfor %}

But isn't there a better, optimized way to do this without hitting the database every time I get a subquery by status, and without iterating over the objects list multiple times?

score 3 · Accepted Answer · answered Sep 17 '14 at 21:09

You are looking for the regroup filter

{% regroup object_list by status as games_list %}

<ul>
{% for game in games_list %}
    <li>{{ game.grouper }}
    <ul>
        {% for item in game.list %}
          <li>{{ item}}</li>
        {% endfor %}
    </ul>
    </li>
{% endfor %}
</ul>

You might have to customize the way the elements render, but I will let you figure that out yourself.

Django - Divide query into subgroups by attribute

1 Answers1