# models.py
from django.db import models

class Campaign(models.Model):
    name = models.CharField(max_length=20)

    def __unicode__(self):
        return unicode(self.name)

class Category(models.Model):
    campaign = models.ForeignKey(Campaign)
    name = models.CharField(max_length=20)

    def __unicode__(self):
        return unicode(self.name)

class Account(models.Model):
    category = models.ForeignKey(Category)
    name = models.CharField(max_length=20)

    def __unicode__(self):
        return unicode(self.name)

# admin.py
from django.contrib import admin
from models import Campaign, Category, Account

class CampaignAdmin(admin.ModelAdmin):
    list_display = ('name', 'related_accounts', )

    def related_accounts(self, obj):
        from django.core import urlresolvers
        url = urlresolvers.reverse("admin:<yourapp>_account_changelist")
        lookup = u"category__campaign__exact"
        text = u"View Accounts"
        return u"<a href='%s?%s=%d'>%s</a>" % (url, lookup, obj.pk, text)
    related_accounts.allow_tags = True
admin.site.register(Campaign, CampaignAdmin)
admin.site.register(Category)

class AccountAdmin(admin.ModelAdmin):
    list_display = ('category', 'name')
    list_filter = ('category__campaign',)
admin.site.register(Account, AccountAdmin)

admin/yourproject/account/?category__id__exact=<category.id>

def account_link(self, obj):
    return '<a href="/admin/yourproject/account/?category__id__exact=%s">Accounts</a>' % (obj.category.id)

account_link.allow_tags = True

list_display = ('account_link', ...)

from consensio.models import Account
from django.contrib import admin
from django.conf.urls.defaults import patterns, include, url

class AccountAdmin(admin.ModelAdmin):
    campaign_id = 0;

    def campaign_account_list(self, request, campaign_id, extra_context=None):
        '''
        First create your changelist_view wrapper which grabs the extra
        pattern matches
        '''
        self.campaign_id = int(campaign_id)
        return self.changelist_view(request, extra_context)

    def get_urls(self):
        '''
        Add your url patterns to get the foreign key
        '''
        urls = super(AccountAdmin, self).get_urls()
        my_urls = patterns('',
            (r'^bycampaign/(?P<campaign_id>d+)/$', self.admin_site.admin_view(self.campaign_account_list))
        )
        return my_urls + urls

    def queryset(self, request):
        '''
        Filter the query set based on the additional param if set
        '''
        qs = super(AccountAdmin, self).queryset(request)
        if (self.campaign_id > 0):
            qs = qs.filter(category__campaign__id = self.campaign_id)
        return qs