django-admin: Add extra row with totals

Question

I\'m using the standard django admin module to display a list of rows. One of the columns is a numerical field. I\'d like to display an extra \'totals\' row that has most of

Answer 1

I think the Django way to do this is to override the ChangeList class which django's admin app uses. You do this in django 1.2 by calling the get_changelist method in your admin class. In my example: TomatoAdmin calls this method returning a custom ChangeList calss. This ChangeList class: MyChangeList simply adds an extra attribute to the context of change_list.html.

Make sure that change_list.html is in the following directory:

app_label/change_list.html

in the example this is: templates/admin/tomato/change_list.html

models.py (A simple model with an integer field)

class CherryTomato(models.Model):
    name = models.CharField(max_length=100)
    num_in_box = models.IntegerField()

admin.py (your Admin class and a custom ChangeList class)

from django.contrib import admin
from django.contrib.admin.views.main import ChangeList
from django.db.models import Count, Sum

from tomatoes.tomato.models import CherryTomato

class MyChangeList(ChangeList):

    def get_results(self, *args, **kwargs):
        super(MyChangeList, self).get_results(*args, **kwargs)
        q = self.result_list.aggregate(tomato_sum=Sum('num_in_box'))
        self.tomato_count = q['tomato_sum']

class TomatoAdmin(admin.ModelAdmin):

    def get_changelist(self, request):
        return MyChangeList

    class Meta:
        model = CherryTomato

    list_display = ('name', 'num_in_box')

admin.site.register(CherryTomato, TomatoAdmin)

change_list.html (relevant bit only, copy/paste the existing one and extend it)

  {% block result_list %}
      {% if action_form and actions_on_top and cl.full_result_count %}{% admin_actions %}{% endif %}
      {% result_list cl %}
      {% if action_form and actions_on_bottom and cl.full_result_count %}{% admin_actions %}{% endif %}
      Tomatoes on this page: {{ cl.tomato_count }}
  {% endblock %}

I'll leave it up to you how to style this the way you want it.