Django Nested Regroup Example (Group by category foreign key, then month of start date)

gistfile1.mustache

#views.py

def events_index(request, year):
  selected_year = Year.objects.get(title=year)
  events_list = Event.objects.filter(year = selected_year.id).order_by('category','start_date')
  return render_to_response('events_list.html', {"events_list": events_list})

#events_list.html  

{% regroup events_list by category.title as events_list_by_category %}
  
  {% for category in events_list_by_category %}
    <hr>
    <h2>{{ category.grouper }}</h2>
      {% regroup category.list by start_date.month as events_list_by_month %}
        {% for month in events_list_by_month %}
          <h3>{{ month.grouper }}</h3>
          {% for event in month.list %}
            <h4>{{ event.title }}</h4>
            <p>{{ event.start_date }}</p>
            <p>{{ event.category.title }}</p>
          {% endfor %}
        {% endfor %}
  {% endfor %}

This does not work well with postgresql