Django - Adding row to the admin list with the totals and averages of given fields

Once a while a wild ticked occurred for one of the projects I was developing.
The issue was that they needed a rows with the totals and averages to be displayed at the end of the table in the admin changelist view for particular fields.
So here how it works

from django.contrib.admin.views.main import ChangeList
from django.db.models import Sum, Avg
 
from myapp.models import MyModelName
 
class TotalAveragesChangeList(ChangeList):
    #provide the list of fields that we need to calculate averages and totals
    fields_to_total = ['amount', 'total_sum', 'paid_by_cash',
                       'paid_by_transfer',]
 
 
 
    def get_total_values(self, queryset):
        """
        Get the totals
        """
        #basically the total parameter is an empty instance of the given model
        total =  MyModelName()
        total.custom_alias_name = "Totals" #the label for the totals row
        for field in self.fields_to_total:
            setattr(total, field, queryset.aggregate(Sum(field)).items()[0][1])
        return total
 
 
    def get_average_values(self, queryset):
        """
        Get the averages
        """
        average =  MyModelName()
        average.custom_alias_name = "Averages" #the label for the averages row
 
        for field in self.fields_to_total:
            setattr(average, field, queryset.aggregate(Avg(field)).items()[0][1])
        return average
 
 
    def get_results(self, request):
        """
        The model admin gets queryset results from this method
        and then displays it in the template
        """
        super(TotalAveragesChangeList, self).get_results(request)
        #first get the totals from the current changelist
        total = self.get_total_values(self.query_set)
        #then get the averages
        average = self.get_average_values(self.query_set)
        #small hack. in order to get the objects loaded we need to call for 
        #queryset results once so simple len function does it
        len(self.result_list)
        #and finally we add our custom rows to the resulting changelist
        self.result_list._result_cache.append(total)
        self.result_list._result_cache.append(average)

And all we need is just to set our custom changelist to the AdminModel

class MyModelNameAdmin(admin.ModelAdmin):
 
    def get_changelist(self, request, **kwargs):
        return TotalAveragesChangeList
 
admin.site.register(MyModelName, MyModelNameAdmin)