python 41 lines · 1 tab

Django aggregation with annotate for statistics

Priya Sharma Jan 2026

1 tab

from django.db.models import Count, Avg, Sum, Q, F
from django.views.generic import TemplateView
from products.models import Product, Order, OrderItem


class DashboardView(TemplateView):
    template_name = 'analytics/dashboard.html'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)

        # Simple aggregates
        stats = Order.objects.aggregate(
            total_revenue=Sum('total_amount'),
            average_order=Avg('total_amount'),
            order_count=Count('id')
        )

        # Annotate each product with sales stats
        products = Product.objects.annotate(
            total_sold=Sum('orderitem__quantity'),
            revenue=Sum(F('orderitem__quantity') * F('orderitem__price')),
            order_count=Count('orderitem__order', distinct=True)
        ).filter(
            total_sold__isnull=False
        ).order_by('-revenue')[:10]

        # Conditional aggregation
        order_stats = Order.objects.aggregate(
            completed=Count('id', filter=Q(status='completed')),
            pending=Count('id', filter=Q(status='pending')),
            cancelled=Count('id', filter=Q(status='cancelled'))
        )

        context.update({
            'stats': stats,
            'top_products': products,
            'order_stats': order_stats,
        })

        return context

1 file · python Explain with highlit

Aggregation performs database-level calculations efficiently. I use aggregate() for single results across entire queryset (like average or total) and annotate() to add calculated fields to each object. Common aggregates include Count, Sum, Avg, Min, and Max. I combine annotate() with filter() to create conditional aggregates. F expressions reference fields in aggregations. This pushes computation to the database, which is much faster than Python loops. For complex stats, I sometimes use raw SQL via extra() or direct cursor, but aggregates handle most cases elegantly.

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